Very cool video - thanks for posting the link
Never with a shark, but I had two similar circumstances. Once was off the coast of Prince Rupert, BC I was fishing for Coho salmon and a seal took a big huge bite while I was reallying it in. I eventually got the salmon in with big teeth marks on the belly and a chunk missing.
Another time was fishing for rainbow trout and had a small fish on the line. A big bull trout came along and ripped the fish right off the line. When I reeled in the line all the was left was a piece of the lip of the rainbow!
Pete