Nope...First, the tree's natural response is triggered by exposure to oxygen so you need the edges of the wound to be exposed. Just leave it open. There is some evidence that trichoderma fungi are antagonistic to decay fungi. However, there really isn't good understanding of how those are best applied, etc...
You can't seal it "enough" without some pretty nasty chemicals (think pressure treating) - and even then, decay fungi eventually win. If that could prevent the tree from rotting , why not use it on every deck and fence rather than pressure treating wood?
The guy in the video doesn't seem well versed in tree care/biology:
1) Trees don't die from decay as he says in the beginning of the video. In fact, large cavities often result in very little strength loss.
2) Trees never heal. They compartmentalize. He refers to "healing" several times.
3) He says they don't cover living tissue (about 2:30) WHILE showing painting over the edges of the pruning cut where there is living tissue.
Fungi are microscopic and airborne, so you aren't going to seal it well enough.
