Video issue

I have a problem with playing videos. Some students can not read the videos or load the videos, while others do not have problems. Those who have trouble to read the videos can easily read the videos on youtube, dailymotion etc ... Can I have any help please ?

Probably need more info

I don't have any specific solution but there are so many variables involves when it comes to client's browser support. I'm sure anyone who like to help would like to know at least the following from your students. - what web browser and version are they using? - what OS and OS version? - are they seeing any javascript error? - did the player load and the video didn't play? - are you using flash player or the opigno video module or the external video module or others? - those who can watch the video on youtube and not on your site, is it he same video you are referring to or they can just generally watch video on youtube, dailymotion and etc?