Thank you for using DVD Catalyst,
Did you change any settings, other than selecting the NOOKcolor profile?
When you try and test-play the videos on your computer (they should be located in your "Videos" or "My Videos" folder) do they play then?
There are 2 ways f playing videos on the NOOK, which can also make a difference.
The Gallery app finds and displays movies located anywhere on your NOOK, however, it is a bit picky in where they are located when you try to play them. Try going into Library > My Files, and play your videos from there.
Near the bottom of the NOOK guide on my website can provide you a bit more details on that:
I have put movies on my Nook Color SD Card using your program to convert the fiels. I have lost the movies twice. Gone to watch them and they are gone. Reloaded them, they worked..then later gone again. I think its happening when its turned off/on.
Any ideas on how to fix this?