First post, this is going to sound like a phishing attempt from a bot 
For my own private needs i’ve build a small standalone desktop app for linux (python,qt,opencv based - so portable to mac/windows)
i mainly watch 8K videos.. which doesnt play nicely AT ALL in the browser based solutions on my 10 year old linux desktop… so i made my own
manual action point setting, the option to trim/pad scripts if you download a script but have a remastered video file..
but the most important thing .. click “zoom” and it buffers 20-30 seconds so you can smoothly move frame by frame - even an 8k video on old shitty hardware…
if anyone is interested in providing feedback for a beta version ping me, otherwise i expect to publish for linux later this month