Jab 1 is not frame 1 and I don't think dash attack is frame 5. When you were analyzing Captain Falcon's introductory video, did you make sure to set the quality to something with 60 FPS?
The instance when Captain Falcon uses jab 1 already has him in the middle of its startup. The frame before his jab 1 connects with Samus has him in a pose like a boxer about to throw a jab. The next frame is when it connects, so at most, it's frame 2 not frame 1. If it was frame 1, you would not see the previous frame. It would be Captain Falcon's idle animation and immediately, on the next frame, frame 1, jab 1 would be out, but it's not.
As for dash attack, same thing, the clip is introduced in the middle of Captain Falcon's startup animation for dash attack. We don't see him running before in that instance, not the clip before when he runs and the video cuts to the next clip.
The only moves I would be sure on checking their startup from this video would be Up Smash, Nair, his new Side Smash, and reverse Falcon Punch. Maybe Falcon Dive, but it's a bit weird since he grabs Fox up high and Falcon Dive is able to grab people at ground level since its active frames begin earlier.
In the Smash Ultimate Direct, Captain Falcon's section does show him doing a rapid jab combo and regular Falcon Punch. In that video, jab 1 is frame 3 just like in the previous games. The starting frame is right after Captain Falcon's landing animation where he suddenly stands up, leans forward, and puts his hands up like a boxer. From there, Duck Hunt gets hit on frame 3. Frame 2 looks like the frame of animation from his introductory video when it cut to there.
