The thumbnail of the first video is just clickbait, with the conclusion at the end of the video being that Trotsky wasn't right or completely vindicated about everything and that Trotsky and Stalin both used the history of the Soviet Union as a weapon for political and ideological orthodoxy.

Here's the transcript of that conclusion

Now, am I trying to argue that Trotsky was right about everything after all and is completely politically vindicated? No, not at all. Rather, this is just an illustrative example of how in the 1920s, Soviet history itself was one of the key weapons wielded in the battle for political and ideological orthodoxy. As the ongoing historiography series will illustrate, Stalin cultivated a certain historical narrative that was favorable to himself and his goals. Well, Trotsky did the same. In the former's case, a considerable industry emerged of party committees, government departments, press outlets, even entertainment. The school of falsification, if you will, which wrote and rewrote the history of the revolution. This school censored or suppressed certain pieces of evidence, canonizing one interpretation to the detriment of others, and in the process worked to cement Stalin's position as the school's leading professor.

I just finished the first video and, knowing nothing about any of this, I'd like to be pointed towards the direction of any refutation or criticism of the contents of the video.

I guess I don't know the first thing about Trotsky.

Ahhhh

Re the 2nd video:

As the story goes, Stalin was Lenin’s right-hand-man and the person slated to succeed him upon his death. Or if not Stalin, sometimes emphasis is placed on Leon Trotsky as a possible alternative. However, in actuality there was a man more senior than both Stalin and Trotsky, a man who was Lenin’s original right-hand-man: Yakov Sverdlov. Up to his untimely death in 1919, Sverdlov held the reins of the Secretariat, placing him in a position to succeed Lenin if the opportunity arose. He was effectively Stalin before Stalin, serving as the blueprint for the latter’s rise to power.

I figured as much, but that doesn't mean absolutely everything this person says is bunk.