John Flynn, who makes the Flynn frame, has promoted this idea for years. I can see how it could help in some situations, but there also some serious drawbacks to watch out for. Long seams on the bias are going to stretch unless you're extremely careful. Just cutting a long seam on the bias can be problematic, since our workspaces and cutting tools are generally designed for handling smaller pieces, and it's much easier to fold and cut something on the grain. (Notice how many people are involved in cutting this piece in the video.) You also need to be aware of the math used to determine whether your fabric will be big enough for your quilt back when it is pieced this way. John Flynn's instructions can be found
here. I'd be interested to hear whether anyone here has actually used this method, and how they liked it.