Dinobot is a Predacon who sided with the Maximals because he is a brutal, savage warrior but with a mega honor code that his Predacon fellas did not cared about but the Maximals could at least understand.
He wasn't received with open arms, and he was constantly arguing with the other Maximals over their "soft" nature, especially with the sarcastic Ratrap, who always suspected Dinobot would betray them to the Predacons at the first chance- and Dinobot eventually does it, but he regretted that choice and did everything he could to fix his dishonorable action and recover the Maximal's trust.
Eventually, Megatron gets his hands on a golden disc that contains information about the future, and uses it to change history- because see, the entire series happens during prehistoric times on Earth, and Megatron plans to locate and wipe out the first evolved apes to snuff mankind on the bud, so humans would never exist and so, would have never aided the Autobots to win the war against the Decepticons.
Dinobot ends up finding the golden disc, figuring out Megatron's plans and finds something else- the day and reasons of his own death, which terrifies him because it's a fate he seems to be unable to fight off or avoid.
The video you watched is the moment where Megatron starts his attack and Dinobot accepts to fight the Predacons before it's too late, fully knowing he will not survive- but he choses to do it anyway and he succeds, ruining Megatron's plans and saving future mankind at the cost of his own life.
He dies surrounded by his Maximals friends, admiting he always liked Ratrap and asking him to tell his story with the good and bad parts untouched, so future generations could judge him accordingly.
And then he dies.