What is “my library”, what are you using to play them? Which OS and hardware. TG and X both transcode the videos, both are paid organizations with bunch of people and budgets, so can’t compare here.

Nostr is just a bunch of JSON (text) and has nothing to do with any sort of binary files. Also, Nostr has unreasonable standards for maintaining integrity of the uploaded media, disallowing media hosts to “fix” or “make smooth” your video even if we were swimming in cache and ads revenue to be able to do so