How come movies/video games decrease the motivation to do buddhist practises? I practised buddhism a lot in holidays given due to Covid-19. I listen to dhamma and meditate each and every day. When my college started, I was not ready for the exam. I got stress. Somehow I found some interesting videos on a video streaming platform and I watched videos such as movies, gaming videos and funny videos. It helped me to forget the problems. At the beggining, I had a lot of resistance to watch that kind of useless videos. But at the end, I lost that resistance. Watching a video became nothing. Even after 2 months gone, I still watching videos. I passed days without doing anything related to buddhism. I can't be mindfull as before.
What happened to me? How those videos cause me to lost my interest for buddhism? How I lost that resistance? Have you any personal experiences like this? How can I get back to that previous state?
What happened to me? How those videos cause me to lost my interest for buddhism? How I lost that resistance?

I suspect something you wrote points to the answer – you wrote that college work stressed you out, and these videos “helped me forget the problems.” People respond to stress in their own way, e.g. overeating, indulging in drugs or sensual pleasure, or zoning out on YouTube videos. They’re all easy distractions that are pleasurable in the short term and an escape from your troubles. As you’ve found, watching videos online can become compulsive – there are always endless more videos to watch, endless suggestions and enticements. It may not cause the same obvious physical downsides caused by overeating or drug use, but there is a definite negative effect as it takes over your time and stunts your motivation for other, healthier endeavors. Internet addiction in general is a very real thing, and perhaps reading a bit about it will give you some insight as to how your mind has been affected by your time online.

How can I get back to that previous state?

Not to get technical, but there’s no such thing as going back to a previous state, nor should you want to. You’re currently learning a challenging but important lesson – distractions will always exist, and now you know that a weak spot for you is internet videos. Guess what? You’re going to get through this, and then you’re going to encounter the next challenge and overcome that one, and so on. And at each step you’re going to become wiser about pitfalls, how to avoid them, and how to climb out of them. I suggest you start by reading (or re-reading) about the five hindrances and their antidotes. Of the five hindrances to progress – sensory desire, ill will, sloth-torpor, restlessness-worry and doubt – you seem to be plagued by a mix of the last three. They each have their specific antidotes, in this case such aspects as rousing energy, having a schedule/routine for meditation, and developing contentment and trust in the process. Underlying all of this are the constants of Buddhism: being mindful of our thoughts and impulses, investigating them to understand them, and detaching from them as you realize they’re not “you” and they’re just as transient as anything.
I believe having a schedule/routine for meditation is critical. As the body and mind get used to it, we just automatically do it and are less likely to skip it in favor of distractions. Keep to the schedule and give yourself time to get in a groove. Don’t beat yourself up if it’s tough at first. I noticed that the election week stress threw me off, and I’m just now getting more focused day by day. Best wishes to you.