It gets interesting at 2:39!
Generally, for crawling, you want solid axles as they force the chassis up and out of the way when the suspension cycles - IS means one wheel goes high but everything else stays low, causing fouling on chassis, diff etc.
It all depends on how much articulation you're after though, what terrain you'll be crawling, where you want the centre of gravity etc.
Don't get too engrossed in having loads of suspension articulation though - when crawlers were first 'marketed' having the front axle twist perpendicular to the rear axle looked great, but it caused a lot of problems with wheels dropping into holes etc.
The action of the suspension is just as important - if you're driving over uneven ground, you don't have to have all the wheels totally follow the terrain as, if the 'diffs' are locked, having a tyre in mid-air isn't a complete disadvantage if the other three tyres have traction - you could stop the wheel that's in mid air, or run it at reduced speed once it detects it's not under any load, so it will at least realise when it's back on the ground.