Every 2/3 uploads I will go back and rewatch/listen to an old video and podcast. I do this to check my progress and also do flashcards of older lingqs.
Does anyone do something similiar? or reviews the same material over and over again until it is completely understood before moving on to a new upload?
Or do you not review old uploads at all and still noticing progress?
I repeat listen to podcasts outside LingQ. Unfortunately LingQ penalises repeat listening, I partially get round that be]y deleting and reimporting videos. I don’t repeat listen many videos. But I do try to listen to lots of videos on a given subject e.g. SpaceX, plumbing, detective films.
I sometimes review old material. I don’t have any fixed plan for this, though. There is a podcast series I have worked through a while ago that I am currently repeating irregularely. I’ve merged all the lessons into a pdf and review them on my tablet, writing translations below those words I haven’t memorized.
I review old stuff if I like to have something easier that I can do for a longer time or that I can actually comprehend, as I usually have around 20-30% unknown word count in new lessons. It’s a good way for boosting ones motivation. If you have the feeling you make almost no progress, review something from 2-3 months ago. You’ll probably be surprised. 
I never review stuff that I have just finished, though. That’s never been my learning style in any subject. But that’s a personal preference.