At 15:50 to 15:54 that is clearly a belt fed weapon firing.
How is it that you differentiate a belt fed weapon from one firing from a magazine with these sounds?
I have heard lots of both, so please explain it to me.
Belt fed have a lower pitch sound to them. To me its like a "thud" sound. More important the LMG uses a 30 round clip. The shooter was firing 50 rounds at a time. When I first heard it I thought it was an M240 (it might be.) I would say it was an M249. Also, note how long it takes to reload:
Also, the fact we can see an M249 LMG in one of the famous pictures.
M249:
https://www.youtube.com/watch?v=UHYd5FpR_yM M240:
https://www.youtube.com/watch?v=UcN7w_gh7uY