The problem is that you need to reproduce the local Excel environment, or the local video rendering environment, in the cloud. That is either something you do on a per-vertical basis or perhaps with some very advanced system administration tricks.
Also, video is probably not a good candidate, because it's data heavy and relatively CPU light. The good candidates for cloud offloading are lots of computation on small data, which does not fit the class of things that most people do on their desktops these days.
I asked some commercial video friends about this once and they didn't seem too interested. Their company invested in a private network for their office and a lot of CPU muscle.