The link in the OP is a link to what POTUS "re-tweeted". That's the way twitter works. The screenshot above shows what POTUS' retweet. When on twitter, clicking that video will take you away from Trump's twitter feed, to Terrence K Williams' twitter feed where the video is. It works that way because otherwise, everything retweeted would get duplicated every time. Hence twitter would have to host, what is now, well over 1 Million duplicates of the same video.