In important things with slow internets. Use linux!
A tool that I often use is youtube-dl and it downloads videos from thoutube in whatever format you tell it to. Then you just play it whenever you want.
Also, it is super easy to have it download them in the middle of the night.
And if its on dtube, you just tell wget to get it.
Makes life on a slow internet a lot easier.
Thank you. That is helpful.