Nice idea but impractical in real life. Accounting firms shred massive amounts of paper every day. For example, at the small CPA firm where I used to work, each employee had a shred box that was periodically emptied by the office runner and shredded. If while making a spreadsheet workpaper I noticed a mistake after printing, I'd print out a corrected version and put the incorrect one in the shred box. If a photocopy came out wrong, the messed up one would go into the shred box. If I realized that a spreadsheet was not designed right or not doing what I wanted to do, it would go into the shred box. If I had too many copies of a paper, the unneeded extra copies would go into the shred box. Tax returns were always generating incorrect forms that needed to be shredded. So there was constant shredding every day of ordinary documents. Now, if a workpaper was corrected or changed by a reviewer, then the older copy would be kept in the file with a big S scrawled on it for superseded behind the corrected version. But, generally, vast amounts of paper with potentially sensitive information are shredded every day in accounting firms. There isn't enough space to store it all nor do you want such info thrown out where an outsider could go through it at a dump. Shredding and burning was the safe thing to do.
Also, employees committing fraud would be aware of the web cameras. They would clearly try to dispose of the documents out of the view of the cameras.
Plus, the cameras and storage of their films would take up a lot of memory space. That equals dollars which means even higher fees for auditing or lower profits for the accountants (which in turn means that that only the least able and most desparate people would be recruited for the job -- possibly creating an even worse potential for fraud).
Finally, web cameras would go beyond the normal employee privacy concerns about internal security cameras. At least those cameras are only viewed by internal security people, not some wierdo halfway around the world (or a competitor).