Because Bieber is such a trendy upstart, when he found out the news that Instagram (which he is a mega fan of) now supports video, he just had to jump on that and get sharing straight away. Only issue? Bieber wasn't really all there.
Now it could just be tiredness/exhaustion/a little bit of drunk, but TMZ and others are suggesting that he may have been smoking some of the wacky tobaccy prior to the video. Arguments for? Well he can't make it through a sentence without giggling, forgets what he's saying and is generally quite glazed in the face. Plus we've had plenty evidence before now that he likes his herbal remedies, what with everything that was found on his tour bus and all those photos of those 'hand rolled cigarettes'.
The video is still live on his Instagram page, so he clearly has no shame about the whole thing (and the fact that there's nothing actually incriminating in the video so why not). Next step, Snoop collab. Obvs.