Is this one file that is seen by the DVD player located at the root of the drive, lowest level such as if the drive was Z: the file would be within the root of that drive at say Z:\video.avi whereas videos that are not found by the DVD player are located in directory trees where the DVD player may not have the ability to navigate depth to access these at say Z:\videos\christmas2014.avi
If this is the case, then you can locate all videos at the root of the drive.
Also I have heard of some players getting choked up on file size where say a 100MB file will play fine, but a 4GB file will not play, and this is because the player reads in the video to local memory before playing because it can not buffer on the fly the data, so if a video exceeds the internal memory of the player then it doesnt matter what format the video is, its clearly too large to be played.
If this were the case then you would want to use a software package such as Wild Media Server to share videos from computer to the player which would stream and buffer the data between the player and the computer. Someone here pointed me to this program when i was having troubles and it works really well.
http://www.wildmediaserver.com/