Yes, there are thousands of people out there creating gameplay videos on YouTube. Why another?
Mainly, because of my kids. They’ve wanted to create a YouTube channel for a while, and videos of games seemed like something fun that we could do together. We all like playing games, although sometimes different games. Recording and uploading screencasts is something that we can do together.
I’ve played around with gameplay videos on my Android for a while. Never got much traction, but it’s still fun. Now that the kids have an XBox they’re creating videos of Minecraft and other games.
So, the TL;DR version, it’s just fun.