Agreed, also I think he's breathing into the bag not out of it. If you have a flotation device that's not fully sealed then you need to periodically re-inflate

Agreed, also I think he's breathing into the bag not out of it. If you have a flotation device that's not fully sealed then you need to periodically re-inflate it a bit. It's the equivalent of keeping a leaky boat afloat by bailing water.