The biggest benefit is additional sleep. Of course as you just saw in the video...if baby wants to play, well, no one is getting extra sleep.

But now lets assume baby DOES want to sleep. Well, when baby fusses in the middle of the night, you can just cuddle your baby a little closer, and she will calm down and ideally fall back asleep. If she's hungry (and mom breastfeeds), mom can feed in the side-laying position and get some shut-eye while baby sleeps. Some babies "self-serve" during the night as well, if mom's breasts are exposed, and mom may not really even wake up. Many parents feel that their baby generally just sleeps better with them (which makes sense, I mean, just about everyone experiences the "baby will only sleep in my arms/on my chest" thing).

Since we're on /r/daddit, I'll assume that you are dad. You wouldn't roll over on your son because safe co-sleeping guidelines state that baby should not be inbetween mom and dad (or whatever two adults are in bed). It should be baby and dad on the outside, and mom in the middle. Mom should sleep in a heavy top because she should not use blankets near the baby. The mattress should be fairly firm. Pillow needs to be kept away from the baby. No smoking in bed. Mom should not be a smoker nor have been drinking before bed. If mom is an extremely deep sleeper, or a "thrasher", then co-sleeping isn't safe (don't want to punch or kick the baby while sleeping). Also, anecdotally, many mom's notice that when baby is in bed that while they do sleep better, they also sleep more lightly, and are more aware of the baby.

Once the baby gets a bit older and mobile and wants to play, many parents find that co-sleeping becomes less enjoyable. You see what you saw in the gif above, or you find that your baby just moves a lot in their sleep. This often coincides with 6ish months of age, when sleep training is a-ok. So you can totally go from co-sleeping to sleep training at about this time too!