Cant comment on the flashcards, but I imagine them being no different from anki or FA--just seeing the info multiple times over and over essentially, which helps. I think they also have some algorithm where they incorporate spaced time repetition, but I'm not completely sure what the exact format or layout is.
I have gone through +90% of the express videos and plan on finishing them up soon. I think that they're great, especially when considering the value (DIT is like $800 and the package with the Rx bank + cards + videos is less than half of that). I never watched the videos until I finished that subject material in class, and I learned some concepts in their videos that were really helpful and even better taught than a lot of my lectures. This was after I had done well above average in my courses at school to begin with. I wrote down notes only if they helped me understand something better in FA since FA is a text with a lot of bullet points and not much context. I now have my FA annotated where I know I understood every single page at one point, and whenever I refer back to pages, I have my notes there that help solidify everything. I can easily read 50+ pages a day on top of doing other things, and this is on my second run through the material. My first run through FA was slower than others, but I can get through the text much more quickly and come away with a better grip on understanding the material better than I could have if I had just skimmed FA once on my own. The big key I think is to use it to cover material you've learned before in class.
If you're an auditory learner, then I'd recommend it. At the end of the day, the readers stick to what's in FA besides expanding on the material when they try and clarify a topic, which I think is a plus because if you understand everything in FA, you should get a great score on step 1. Keep in mind that the videos cover like 80-90 hrs, so it takes time, but you can always 2x it. It's certainly not the only way to learn the material from FA, but I think it's a great resource to use to get through FA.
At the end of the day aim to understand FA and do 4k+ questions to optimize your step score. If you like express then stick with it, but if it's not clicking just drop it.