Some videos dont wanna load on wordpress

I don't understand the issue. They are mp4 videos but from 10 of them only one works. I used easy player, osmedia player.
But when i use regular wordpress playlist option then all videos from library work without any issue. However that's not what i wan't to use.
Thanks for all the replies

not really clear with the details given here, if u really need any help, i can help u to look into ur site, let's discuss in details via PM