I’m not very familiar with S1 data, but I think you don’t see masks because there are no mask defined by default for this kind of product. In the video tutorial a MERIS product is used. This one has masks defined by default.
But you can create your one masks as explained in the tutorial.
I think the internally created mask has product-width, which corresponds to width of the
Deburst-image for Sentinel-1 IW. So you will never see this mask within one of the separate
After creating a Deburst-product (Radar/Sentinel-1 TOPS/S-1 TOPS Deburst), the Mask Manager
was filled as expected.