That's the technique that I use to get up after working under the van. I usually take a pillow with me to help with a stiff neck when lying on my back working on whatever.
But then you aught to see me helping my fishing mate get out of his sit inside Kayak.
Getting into my Mazda3, I have to put my bum in first, swing in the left leg & then use my hands to lift in the right leg. Getting out is always the legs first & then push down on the seat & dash to lever the body out.
Just a bit more dignified than he method in the vid.