It happens we're about to do a backup video, where I'll show a lot of what I do on the video that you have.
Any roll you know will fit to the beats we're doing. The speed is about 70 or 75 beats a minute, with TWO beats per 8-note roll. Just make sure every roll starts where there is a beat. Listen to the bass notes for where the beats are located.
If you feel you need more guidance than the above, you might try getting my one-hour DVD Get Rolling, which shows exactly how to synchronize rolls to a typical bluegrass rhythm. The speed on the two videos is about the same, so if you get the hang of it with Get Rolling, you can then play along with both videos.
I hope that helps!