Thanks for your feed @jonathan.
I have already discovered the problem, but only now had the chance to explain it.
Because of the screen sizes on iPhone 7 plus and a certain Huawei model (my clients phones), when watching on landscape, the video didn’t show (only a blackscreen) because i had the breakpoint between 400 and 700px (measures i usually use on mobile layouts) and 700 to 2000px (desktop layout). I changed the 700 to 800px and the problem was solved.
Basically, on landscape on the responsive layout, it was showing a part of the desktop layout (black background) and so we couldn’t control or see the video.
Also, like you said, because i have 2 different sizes of the videos (mobile and desktop) and when jumping to desktop layout, it loaded the bigger video, which takes longer to load.