By the title it's pretty obvious:

I'm doing a giveaway over at my channel.
The available prizes are:
1. $20 PSN Card
2. 2100 Microsoft Points
3. My Dazzle with an S-Video Cable

How to Enter:
1. Subscribe to my channel: [ Register or Signin to view external links. ]
2. Comment on the video and say which prize you'd like to win.

Happy Winning!