That's a great video.
The first stage rockets on satellite launches are very expensive to manufacture and if you can recycle the first stage rocket for multiple uses you can cut down the cost of launching satellites by a significant amount.
One of the legs failed in this touchdown causing the collapse.
If there's a flaw in a design the universe will expose it in some way, now it's up to the engineers to fine tune their design and make it more bulletproof.
They've successfully re landed these stage one rockets many times already during testing phases.