Personally I would just solder them with standard multi core solder.
There doesn't seem much room to get the soldering tip onto the tab of the device so I would think of cutting the legs shorter so you could move the device across a bit. Beware of the extent of the tab on the back of the device so it doesn't short to the pads for the leads.
I wouldn't hold the iron on the tab for the length of time in the video, just long enough for the solder to flow on the exposed area of the tab and pcb pad.
Thinking about this, I may need a better soldering iron if I continue with this project. My current Maplin one only has fine tips, so will not be best to solder Mosfets. I do have a fixed temp iron, but that is only 25W, but has a wide tip.
Apparently it is a Duratool D02265, so I should be able to some better tips.
I only use one size and vary solder size for small parts, 0.3mm for smt stuff. I reckon I'm heading towards needing magnification for the smaller stuff soon. Ican still manage 0603 without any trouble, but i can tell my focus isnt what it was.
Useful to have different tip sizes, looks fine what you did there.
I am annoyed one of them ended up wonky.
If it works I wouldn't worry about it. I know from recent experience that this gets easier the more you do. When I started I bought some dirt cheap resistors and pcbs from ebay just so I could practise my soldering. Cost about£5 for a load of them . Really helped.