Many users on codeforces are uploading screencasts to youtube. During my past years as a participant, I never watched much screencast, and I think the same is true for many of my friends. Screencast just isn't popular or widespread among Chinese OI or ICPC participants.
So, though I found that these are truly valuable videos for improving performance, I still don't fell sure about how I should watch them. How are screencasts supposed to work? Should I watch one from begin to end for 2+ hours? What are the benefits and how can I get the most out of screencasts?