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.