If you want CM7 yourself, check out my Complete Guide to Installing CyanogenMod 7, which covers the basics of installing on an SD card and issues you may encounter along the way!
CyanogenMod 7 (CM7) was released yesterday and I put it on my Nook Color this morning. Video playback has definitely improved, seems "normal" now. CM7 is amazing, a definite improvement over the Froyo install, in particular because there is Bluetooth and I can go back to using my beautifully awesome iGo Stowaway foldable keyboard! For anyone contemplating moving to CM7 I strongly recommend it. It's not without its faults (seems less stable than Froyo, more "force close" app crashes for me), but the good is worth the bad, especially because very active development will likely address the flaws in the near future; if you don't plan to keep CM7 updated I'd still with Froyo or even wait for Barnes & Noble's official Froyo release next month.
Here's my sweet Nook Color CM7 setup with iGo Stowaway Bluetooth keyboard, I am a master of my mobile domain!