Many of the recordings are at astronomically high wagers (in some cases even $25-50 per spin), stakes that many people who only gamble recreationally will ever consider. In some cases, the video creators are even kicked out of or banned from casinos, and they rant about how this is unfair (search for Sdguy1234 for examples of this). I've noticed that many of the videos contain comments suggesting that security doesn't allow video recording at the slots, and they have to be sneaky with the recordings.
Many of the videos beg the viewers to like the channel and to subscribe. When a video maker wants to show a bonus round only lasting 4 minutes, 'live play' or multiple bonuses are appended to the main content to reach the 10 minute minimum. so clearly these videos are being uploaded to earn their creators money. Most of the videos are just barely over 10 minutes in length, the minimum length for a YouTube video that can be monetized to earn the creator revenue from the ads shown with the videos.
If you go search for 'slot bonus' you'll see countless videos of people winning at casinos, many with audio commentary and professionally done graphic overlays and editing. Can someone explain to me the situation regarding videos on YouTube of people playing slots?