Using Commercial Music in a Video

[Lisa Kirsch]

Hi everyone, I'm new to the list so I apologize if this has been 
discussed before...
I'm planning on starting a small business early next year and I hope to 
offer photo montage videos and other similar services. I've been doing 
some occasional research for what I need to do, but one question 
remains: can I use commercial music? I'm pretty sure I've figured out 
that I can't take a song that I have (unless it's royalty-free) and use 
it with the video, but other sites seem to suggest that it's okay to 
use commercial music from the customer's CD. Is this correct? If so, is 
it because they own the song and I'm just essentially giving it back to 
them with the video? Thanks a ton in advance for any help.
--Lisa Kirsch