You might try a google search; I'm sure there are lots of discussions of this;
briefly, +R and -R are simply 2 different formats; -R usually has about 90% compatibility with most players, though that number is going up as older players are replaced with newer. +R can have 99% or better compatibility if the DVD is burned with the DVD-ROM booktype.
DVD-ROM refers to DVDs that are stamped with the content, rather than burned.
DVD Video really refers to the format that the video & audio information is put on the DVD - it means the DVD is designed to be played in a set-top player, compared with a data DVD which is mainly for use in a computer.
Thanks, guys, the information and website made it a lot clearer. One of the things that caused my confusion was Ulead's use of the terms: DVD-VR and DVD+VR. I had never run across these terms. I am assuming they are the same as DVD-R and DVD+R. Is that a safe assumption? I did not realize the term DVD-Video meant the video that is or is to be recorded on a DVD disk