Definately takes a lot of practice, and i mean a lot. Not so much at home by yourself, but in match play, so you get used to the pressure of messing it up. This will build your confidence, which after the practice at home, should be the only thing holding your skills back.
In any case, i didn’t watch the video, but I do have some decent advice on the topic:
First of all, they don’t do much damage, in a given situation, you’ll get off another 8 damage i believe for landing 2. The first one doing around 5, the second around 3.
Secondly, it’s a lot harder to land 2 then it is one; likewise even harder to land 3. So instead of risking the flashy extra 3 damage, it would be safer to go right for the next portion of your juggle: mk dashing upper, f. mk X fp upper, sh. k ssb.
Keep that in mind!
When doing multiple cr. rh juggles to characters like chun etc. it’s easier for me to do the cr. rh, jab machine, cr. rh, jab machine pattern in that order. And it looks great!
Against the non juggling cr. rh characters, i go for but one jab machine, and then do whatever depending on what character they chose. Unless i know i’m gonna just own the guy, i’ll never go for 2 in a row.
Hope this helps.