I found this "fix" on AB-FORUM - updated exteplayer3 and ffmpeg versions. After updating to these, I have my YouTube addon work again in FHD.
Tried this on the following images : PurE2 7.4, PurE2 6.5, OpenATV 7.5.1 ... on Octagon SF8008, Axas His Combo 4K, Vu Zero ...
1. If You have some previous versions installed ( for example 175 ) You need to remove them first using telnet commands :
opkg remove --force-depends ffmpeg - 175
opkg remove --force-depends exteplayer3 - 175
2. reboot Your box :
3. You must install in this order ( the example is for ARM ) :
( use "--force-depends" if the installation does not go through )
opkg install --force-depends exteplayer3_177_armv7ahf.ipk
opkg install --force-depends ffmpeg_177_armv7ahf.ipk
4. reboot
5. Setup Your ServiceApp like this :

6. Setup Your YouTube like this :


Download for ARM box :
https://www.dropbox.com/scl/fi/avfjqiuf ... 8iszi&dl=0
https://www.dropbox.com/scl/fi/4dnc9ut8 ... 2vkjf&dl=0
Download for MIPS box :
https://www.dropbox.com/scl/fi/wctb5xws ... xq915&dl=0
https://www.dropbox.com/scl/fi/b9zhx2gp ... gmukd&dl=0
I do not take ANY CREDIT for this, this helped me so I hope someone else could benefit too from this update.
The addon was posted by the user Warder, and was rewritten by the user Archivczsk - from "https://www.ab-forum.info"
EDIT Masta2002: Github Link to this Plugin is https://github.com/archivczsk/archivczsk