Quoted:
http://i6.photobucket.com/albums/y232/Alpha-Romeo3/Hunting%20CAR%2010X7/LMT_M4_FDE_XTM_LH_L363ASF-CR.jpg

I did it almost like in your second video link but I didn't have to cut the front end, on my Vickers sling I just used the included Fastex male side connector, then I bought an optional SOC-C (BFG) push button adapter and connected it to the front Fastex buckle of the sling, it makes a cleaner setup no more loose webbing end.

At the rear end of the sling I also usually mount it at the right side of my buttstock (like in your second video) to avoid strangling myself with my sling when shooting my support side shoulder, I only mounted it on the left side for the picture so the entire sling is visible.

The only slight thing I don't prefer with the SOC-C adapter is that they used a smaller diameter push button on the built in swivel, I prefer the larger diameter push button like the one I'm using on the back end of my sling which is a Daniel Defense brand sling swivel.

I'm surprised someone are also doing the same way that I'm doing it, I just learned from trial/ error and experiences, I never seen that video before.