The video above is titled as a Mk38 Mod3 Live Fire, but I would like to point out the ballistic protection that is provided the .50 cal. gun crew. The .50 gun shoot starts at time 1:10 and you get a good view of the ballistic protection beginning at time 1:37.
Yes, this is a pet peeve of mine. I have posted about ballistic protection before, here, here, here. and here.
As yet I have seen no ballistic protection for Coast Guard gun crews other than small shields attached to the mounts that provide no protection for the lower body and only very limited coverage for the gun crew (as in the photo below). Clearly suitable protection is available.
Having a gun crew standing out on deck using deadly force without providing easily available protection is not just dangerous to the gun crew, in some cases it may endanger the mission, if the gun crew is disabled.
Air-cooled 0.50″ (12.7 mm) Browning Machine Gun. Picture taken aboard USS Fife DD-991 on 4 July 2002. US Navy Photograph No. 020704-N-0156B-002.
RE: 25mm Mk38 Mod3, I see there was a contract issued recently for more of these systems, for the USN and the Philippines, so DOD certainly has not moved on to a 30mm Mk38 Mod4 yet. (Late addition, see my comment below.)
Below is the written material that accompanied the video.
CARAT Indonesia 2018: GUNEX (B-Roll)
B-Roll of a live-fire exercise conducted with the Indonesian Navy during Cooperation And Readiness Afloat Training (CARAT) 2018. CARAT Indonesia, in its 24th iteration, is designed to enhance information sharing and coordination, build mutual warfighting capability and support long-term regional cooperation enabling both partner armed forces to operate effectively together as a unified maritime force.
INDONESIA, 08.13.2018, Video by Senior Airman Dhruv Gopinath ••♦♦
The Mk 38 MGS is a low cost, stabilized self-defense weapon system that dramatically improves ships’ self-defense capabilities in all weather conditions, day or night. Installed aboard 14 different classes of U.S. Navy ships and U.S. Coast Guard cutters, it is used extensively by the U.S. military as well as by NATO forces.
A major upgrade to the Mod 3 is the system’s advanced electro-optical/infrared (EO/IR) sensor which provides 330-degree surveillance capability and three fields of view. The superior optics allow sailors to monitor the seas and respond to threats even in extremely low light conditions with the benefits of a low contrast, low light level color day camera and an eye-safe laser range finder.
While the EO/IR sensor system is integrated with the Mod 3’s state-of-the-art fire control system, the Mk 38 Mod 3 is unique from other naval weapons because its surveillance system moves separately from the gun system, preventing adversaries from easily knowing they have been detected.
The Mk 38 Mod 3 also provides a range of 2.5 kilometers and selectable rates of fire from single to 180 rounds per minute, and fires all U.S. Navy-approved 25mm ammunition. It can be remotely operated from the combat information center or other protected ship structures, allowing operators to remain safe and out of harm’s way.
Chuck Hill's CG Blog 
Cheapest and lightest way is to use Kevlar 29, but if it is intended to replace ballistic glass or optically transparent shields, than probably the use of a CerMet (i.e. Ceramic Metallic) composite armor like “AlON” (Aluminum Oxynitride) aka “Transparent Aluminum”…
It appears the contract I referred to was for modifications (ORDALT) to existing mounts. Probably too much to hope that they will be replacing the 25mm guns with 30mm. Text below.
BAE Systems Land & Armaments L.P., Minneapolis, Minnesota, is awarded a $24,468,051 firm-fixed-price contract to provide all necessary material and services required for the procurement and support of an ordnance alteration to modify the MK38 MOD3 machine gun system. This contract combines purchases for the Navy (81%); and the Republic of the Philippines (21%) under the Foreign Military Sales (FMS) program. Work will be performed in Hafia, Israel (67%); and Louisville, Kentucky (33%), and is expected to be completed by May 2023. Fiscal 2021 shipbuilding and conversion (Navy) funds in the amount of $19,802,757 (81%); and FMS Republic of the Philippines funds in the amount of $4,665,294 (19%) will be obligated at time of award and will not expire at the end of the current fiscal year. This contract was not competitively procured in accordance with 10 U.S. Code 2304(c)(1) — only one responsible source and no other supplies or services will satisfy agency requirements. The Naval Surface Warfare Center Indian Head Division, Indian Head, Maryland, is the contracting activity (N00174-22-C-0005).
Thinking about what the ORDALT might be, I come up with two possibilities. (1) to provide an airburst to use against UAS, and (2) adding missiles to the mount, probably APKWS.
An airburst could be either using an M19 grenade launcher or perhaps they now have an airburst round for the 25mm. Switching to a 30mm gun could also supply an airburst capability.
Adding APKWS might also be a way to get an airburst capability, but it would certainly make the mounts more effective against swarm attacks.
On the other hand, it may be something much more mundane, that we would not normally be able to recognize as a change.
The CRS Report mentions mounting an Mk.52 Mod.0 7.62×51 NATO Coaxial Chain Gun to the existing Mk.38 Mod.3…
@Secundius, I believe all the Mk38 Mod3 came equipped with the coaxial 7.62mm so I don’t believe that is the ORDALT.
The CRS Report also mentions some Electronics improvements, such as ISL support to provide combat system integration support, “Athena” control, correlation and display…
( https://www.dacis.com/budget/budget_pdf/FY20/PROC/N/4206_39.pdf )
@Secundius, thanks. This line, “P5 / MK38 COAXIAL GUN UPGRADE]: The MK 38 MGS for the OPC Class requirement has been updated to include an attached 7.62mm MK 52 MOD 0 Coaxial Automatic Gun (COAX ORDALT) for Antiterrorism / Force” does appear to make the addition of the 7.62mm to the Mk38 Mod3s on the OPCs an ORDALT.
On an off chance that I may have missed anything on upgrading the Mk.38 Mod.3 for the USCG, i stumbled onto this about a reprieve on the Mk.VI Patrol Boat at least though 2022…
( https://www.navalnews.com/naval-news/2021/04/us-navy-mark-vi-patrol-boats-recieve-reprieve/ )
@Secundius, The link did not seem to work for me. The 2022 budget would terminate the USN use of MkVI.
Sure would like to know more about the ” ATHENA Control, Correlation & Display (CCD) System on OPCs, which provides target queuing for Gun Weapon System engagements” mentioned in the budget document.
“Naval News” is one of those websites where the Link Address either works or it doesn’t, most often then not it “doesn’t”. But typing in “Naval News April 2021 Mk.VI Patrol Boat Reprieve” does bring up the link once Googled! I just did twice and it works fine.
“Athena” on the other hand is a little hard to bring up, simply because I don’t know what the system looks like or who manufactures it…