Just had another look at the video and there are some differences between that way and the way I do it. In essence they are very similar methods, but I prefer mine, even though it is probably slower.
Firstly, I do not use a slot mitre gauge for this. Or for anything else come to that. I loath the things! Just a personal quirk, maight be OK for cutting firewood but not my work oieces thank you.
I use a sliding table. much more control and smoother. Sliding beam table to be precise. ( and it is)
The video shows a cut at the shoulder line then sideways cuts to take arcs out of the timber across to the end of the tenon.
I make the shoulder cut, ( same first cut) then position the work piece in stages a distance of 1/4 or 1/2" further away from the fence ( hard or soft wood. larger or smaller shoulders to make determine this)) in steps to make further parallel cuts to the end of the tenon then repeat on the other side. THEN I will either use the sidways method as shown just clean up or more usually ( and faster) just clean up with a paring chisel.On smaller tenons you can almost rub the waste off with your thumb at this stage before you chisel,. So the sideways pressure on a blade will be negligible.
Also, if I do clean up with the sideways cut, unlike the video I cut/slide in both direction, towards and away from the fence alternately as I move the work slowly forwards. . He actually wastes a move by sliding the piece sideways and not taking a cut!
I do not think a guard is necessary the way I do it, the blade is hardly above the table surface and using the sliding table fence with a toggle clamp means your hands do not need to be anywhere near the action. For those that want it, a guard would be easy to rig up, even a perspex one if you want to work to pencil lines etc.
