The Plunge Cut is the most difficult of saw cuts with any tool. The Oscillating tool can cut quick clean holes in many materials, and finish off plunge cuts started by other tools in tougher materials.
However plunge cuts take some training and some practice to get clean perfect cuts that don't burn or overshoot. Once you get the knack of it, you can make cuts that up to now required a hammer and a hand chisel.
This is a long video, a bit over 20 minutes, but I decided to leave in all the details that get cut out of TV edits to avoid being boring, and of course leaving you wondering how they really did it, and that get cut out of advertising material because the manufacturers never want to show anything less than super simple to do. I think it is useful to see how long it can really take to make a cut, what can go wrong, and the careful details as to how to get it to work right. In fact that is why I prefer the web to TV. Stick it out -- there is good stuff right to the end.
To make it easier to get to what you want to see - or see again - I have divided it into five secitons: 1) Understanding the blades; 2) Deep plunging and hardwood floor problems; 3) Entering the cut; 4) Solving Hardwood Problems; 5) Plunging into Drywall.