Yes.
I watched the video and the pad was just to make the Vader mannequin a little more realistic. Putting a Vader costume even on the muscular Mannequin I use and posted earlier, is way to skinny. Vader looks off. The muscular mannequin gives a good, proportion based to build on. I tried on a regular mannequin and it was a nightmare. I have bulked up my muscle Vader twice and still not there. It need a third to match Prowse's measurements.
As we all know black is slimming, however it is also very unforgiving. I always thought Prowse maybe has the tiniest of a gut, barely, but if you Study Vader ESB and ROTJ Vader I think he has a very small gut in ROTJ. You likely would not even notice in a T shirt, but with that quilted suit and straps, it shows.
Plus he is getting on in years and we all like a cookie.