Autoplay code order matters

I have some videos on a site and have found that it ignores the autoplay instructions if my code is like this:

[video:http://www.youtube.com/watch?v=bePnLLaA0B0 width:500 autoplay:0]

but respects it if the code is like this:

[video:http://www.youtube.com/watch?v=bePnLLaA0B0 autoplay:0 width:500]

It's inconsistent behaviour (!!), but reordering the code like this convinced my code not to autoplay the videos. Weird, but I thought you would want to know.