How did we survive those car trips? We weren't the problem. Better question is how did our parents survive? My kids would drive me crazy if they didn't have DVD players in the cars.
But to answer your question, movies play fantastically on the NC!!!
We have over 300 childrens DVD's backed up onto the home server. I have a program that backs up the DVD, plus runs a routine to convert the movie into .MP4 format, which is compatible with our devices.
FWIW, I take the SD card out of the Nook and put it into a reader and transfer movies that way. You can hook up the standard USB cable, but it takes me 100x longer (no joke).
The program to play movies is built into Android and the NC. It's called "Movies". To be quite honest, I don't see it in my App tray. I downloaded another app from the market that's also called "Movies", so don't know if it overwrote it or not. I don't think so, just something I'm curious about.
I put the files in the Videos directory already on the NC (on the uSD card). To access them, chose the Nook app menu at the bottom, pick Library, go to Videos on SD card, and pick the file you want to watch. Done.
I've also installed Rockplayer, just to see if I like it much better than the stock player. My main issue was finding a player that can catagorize the movies (like with MP3 ID tags), rather than just showing filenames. I didn't see that in Rockplayer.
Realplayer (oh the horror of the PC version) actually is pretty decent, but shows the movie window too small. Didn't keep either.
To be honest, I like the simple interface of the stock app over some that I've downloaded from the market.
Another way of accessing the "Movies" app is to go to "Gallery". Both pictures and movies will both show up and selecting them will launch the appropriate application.
As for ripping movies, I use a program called Magic DVD Ripper. Hasn't seen a DVD yet that's given it any problems, even Disney DVDs rip fine. Technically, that's breaking the DCMA by bypassing the encription on the disc, but I believe that law infringes on the Supreme Court's ruling that allows for personal backup of purchased content. So I don't feel bad about doing it. I don't torrent or copy anyone else's movies. I bought and own everything that we have. No one is going to tell me I can't legally make a backup.