Honestly, I don’t even remember. It was something to do with minor differences in the cursor movements of specific commands.
Anyway, it’s been years, anything may have changed in the meantime. I should probably give it another go, those were simple nitpicks that I was too impatient to tolerate.
It could be an issue with the codecs (browsers are usually pretty limited in what they support). You could try to use a client like Jellyfin Media Player instead. It bundles libmpv, so it plays almost any video format there is.