Like many youtube videos, it's all about the stupid. When learning, always ride with your shoulders in a doorway. Duh. Even when not learning it's a very good idea. After 10 years of it, I'll now ride with just my DS shoulder next to a post. Also, don't ride next to a wall. This guy doesn't know how to mount a bike on rollers, doesn't even know how to position his hands on the bars. Always a good idea to learn how to ride on the road before trying rollers. These are the easy parabolic rollers, too.

If you can keep your wheels on the fog line for a good while, you won't have much trouble on rollers. Just remember: don't steer the bike. Just like on the road, you ride a straight line with small motions of your head or body, not by moving the bars. The faster you go, the easier it is. Rollers are unlike the road in that more speed does not increase the risk of injury in a fall. As you can see from this guy, the story of coming off rollers, leaving a skid mark on the carpet, and hitting the TV is apocryphal. Doesn't happen.