video uploaded on server not playing in browser

uploaded two mp4 videos on the website. when i play that, it not showing the video. it will show like this only. - Removed - these two videos size is above 20MB. also i have few more .mp4 videos with, thats plying fine. - Removed - in this, the videos "slide1" and "slide2" only not playing. - Removed - video details - Removed - what might be the issue? is this format? size? or anything with server side? its plays fine in all media players. also i uploaded in Google drive, Youtube, there its playing fine. Please help.