For what it's worth: In a little over two months of being a member of Roll20, and about a dozen games, not including my own weekly game, nobody has ever considered the video aspect of the chat ability something that was required. Some use Skype. Some use Google Hangouts. Some use Roll20's built-in system. They all use voice. Nobody used video. I haven't seen any real reason to use Skype etc. over the Roll20 system; we played last night (6 players plus 1 GM) solely on Roll20 without a problem. And if you want the best chances to join a random game, learn Pathfinder. It's free, and there are no end of games which use that system. Plus it's easy to learn and has lots and lots of options so you can build any type of character you like. To echo what others have said, learn the basic rules, 'roll up' (create) a few different types of characters, and get the hang of the system. Then join a game, have those characters handy for reference, and roll up a new character for that particular game based on what that game's GM says. Welcome aboard!