it should work. this will only work for her account, since 7198336588873469189 is a video ID from her account. you'll have to change it back to the original function for other accounts.
most of them are encoded as HEVC so they might not show a thumbnail. you can use atomicparsley or ffmpeg to add thumbnails. not something i'm going to add to the code
and you will automatically get thumbnails on all hevc videos after that.
Alternatively you can buy the official hevc windows codec on the windows store for 0.99$ (lol).
If I am looking to download single videos and not scrap/rip the entire profile - which site do you all suggest? Are there sites that "remove" the watermark? Are there some that compress while others don't? Cheers.