Make sure youtube's new url path parameter (?si) is excluded

[Snailedlt]

Youtube has a new url path parameter (?si) for tracking. This needs to be excluded when getting a thumbnail from the video id... so the regex needs to be updated. More info here: https://gist.github.com/rodrigoborgesdeoliveira/987683cfbfcc8d800192da1e73adc486?permalink_comment_id=4672606#gistcomment-4672606

Also, can we shorten the regex to this? (youtu.*be.*)\/(watch\?v=|embed\/|v|shorts|)(.*?((?=[&#?])|$)). Needs to be tested