I believe that you are wrong. If there is a large trend of low multipliets, then the next bets are more likely to be higher because although the 2 games are independent the chance of losing grows less. Think of a coin. The chance to get 2 tails in a row is (1/2 * 1/2) or 1/4. There is a similar effect at bustabit. So yes, I believe that the rounds are linked. You can't predict it, but you can get a greater chance at winning.
I am positive that you are wrong. In a fair random game, past incidences don't influence future events. So saying "its very unlikely that it'll crash low four times in a row" is only true if you are talking about four FUTURE times. Not if any of those incidences has already occurred.
Here's a better example: I flip a coin. It lands tails three times in a row. I get ready to flip it again. Do you think it's more likely to land heads on this flip than tails? Why? The coin has no memory.