We are all underpaid iTunes affiliates now.
If you want to use a popular song in your next video, make sure it is for sale on iTunes (some songs are not - so you need to check). If it's for sale on iTunes, you can expect a roll-up ad-bar at the bottom of your video when the song is playing, even if it is just a clip.
The bad news is that you have to share your advertising message, and if its a really good song (in the mind of your visitor) you may very well lose him right there.
The good news is, your choice of songs and freedom to use them has just grown equal to the size of the iTunes database.
Since YouTube isn't necessarily a money maker for Google, this is one of those expected changes in their format, where the geniuses at Google were presented with a problem (copyright infringement) and turned it into, potentially the biggest affiliate arrangement ever created.
How to add a custom thumbnail image to your Youtube video
How to CUT THE FAT in your YOUTUBE videos
How to add a custom thumbnail image to your Youtube video
How to CUT THE FAT in your YOUTUBE videos