I;ve not played Tekken in a few months and i am more comfortable playing on P2 then P1 on pad but just so you, it took me a quite a few hours just go get those clip. Its extremely hard on pad and wear a glove to help with loosening your grip. So, the first thing you need to get comfortable with is pressing df+2 so practice it until you're comfortable with it. If you've binded L1 to 2 see the df+2 as a single input rather then 2 (df and 2). Once you are able to hit df+2 majority of the time then practice the forward into df+2 by saying forward df+2 fast in your head, like a rhythm. Also, in some clips (pause @0:02) you can see no neutral so its f,d,df+2 and that was unintentional because i tried pressing both f and df+2 instantaniously so it came out without a neutral. Ive not got Tekken currently so its been a while since i've not played and probably lost my execution but don't give up because you need to segment each input and connect it, once you are comfortable with an individual input join it up, its a building process and remember be patient as this is not easy to do.

If i recall correctly, i changed L1 to Triangle to make it easier since you're using the same hand to do both notations.