I haven't been able to get any videos on BitChute to play since the end of 2020 sometime. Is it because the platform needs Flash Player to work? AND, if so, what am I supposed to do to get the videos there and on Vimeo to play? Do I download something else? A replacement for Flash Player?
To my knowledge, Vimeo, YouTube and other major video sharing sites haven't needed Flash Player for years.
There is no replacement for Flash Player. It's gone forever. See the End of Life announcement below.
If BitChute still relies on Flash Player to play video they need to migrate to different technology as Flash Player has reached end-of-life.
Adobe announced that Flash Player was being retired in 2017. Developers had over 3 years to migrate to different technology for their site to continue to work.