Practice, practice, practice. First thing is learn how to get rolling without actually going anywhere. In your driveway start the bike in neutral, pull in the clutch and shift to first gear then let out the clutch just until it starts to move without giving it gas then slightly pull in the clutch. Once you get a good feel for the point at which the clutch engages(when it just starts to move) start giving it a little gas, just enough so it starts to move without stalling then pull the clutch back in and repeat over and over without going more than a few inches. When you feel confident that you won't stall it then practice actually getting rolling which will require giving more gas in a smooth continuous way, if you have an empty parking lot to practice that may be even better. Then work your way up to shifting from first to second and so on. Learning how to stop is also equally important. I didn't watch the video, thought it might be one of those that show how not to ride, you know guys wrecking on their first or more tries at riding.