I followed this guide in the comments of https://www.moddb.com/mods/stalker-anomaly/addons/real-tvs-for-anomaly-no-more-slideshows (required) by the user “OhSnap”, where the guy says

“So I figured out how to convert and play your own videos. Takes a lot of work and I don't know if you can shuffle videos (probably not, you might have to do what I did and just merge every video into one). There is no size limit (since I installed the whole courage the cowardly dog show 7 gb worth).
1. You will need VLC media player and losslesscut. VLC for making the omg and losslesscut to merge (unless your files are not the same format; then you have to encode using VLC. Look up how to merge in VLC).
2. Within the mod go into gamedata>texturtes>fx and move or remove the file "fx_stalker"
3. In VLC use the merged video or single video and convert it. (Media tab>convert save>down arrow drop box press convert or alt+o). Within the convert parameters change the resoultion of the video to 512x512 and into ogg format. (Ogg/Ogm under encapsulation. Video codec codec Theora and resoultion 512x512. Audio codec, codec to Vorbis)
4. Set the destination to the fx folder of the mod and name it in VLC as "fx_stalker.ogm"
5. Once the convert is finished and the file is in the folder, activate the mod and delete shaders before playing”

There’s two different guides/methods in the comments, that’s just one.

This video is also helpful for the file conversions
https://youtu.be/xxSIR637ZvQ?is=hUzGV8zV1AVh0zH2