Tanks in the streets of LA?

I live in a garrison town, so I'm used to seeing military vehicles moving about on the streets (though not usually tanks) but even so there's something a bit weird about this. (.mov Quicktime file) (via TBogg, Americablog and MyDD)

It does appear to me that some of the tinfoil hats are being screwed on a little extra tight in the light of this video. Yes, on first impressions - and especially in the country where Kent State occurred - it does seem rather intimidating but, given that the tanks (though someone on MyDD identifies them as Marine Amphibious Personnel Carriers, to be exact) aren't actually confronting the demonstrators and that it seems to be a pretty major road they're protesting by I'm inclined to apply the rule that cock-up is always a more likely explanation than conspiracy. It seems more likely to me that the tanks were being moved to somewhere else in the city [*] and happened to go past a (rather minor, by the look of the video) anti-war demonstration on their way. The troops in the vehicles seem pretty embarrassed at the whole thing and surely if you want to project an image of strength and fear to a crowd, you tend to back it up with something more than a couple of cops on pushbikes?

[*] - True conspiracy theorists might want to start investigating just where they were going: Tanks moving through the streets of LA, eh? At night? What aren't they telling us? Are they hiding the aliens from Area 51 in the Staples Center?