I’m guessing that Google is blocking the video from being played. Other people have had similar problems with videos and images hosted on google drive. Glide has mentioned that google has an anti abuse policy that sometimes takes affect, so it’s not a great source for hosting and that’s why it works sometimes and other times it doesn’t work.
For your second issue, which browser are you using? Several people have had problems with Firefox. Can you scroll all the way to the bottom on a mobile device?