I had this problem once - it was due to the fact that I had multiple videos (many of which were very large), in one folder. My computer would just hang - I would usually wait until it regained itself then I was able to re-continue as usual.
But what we are going to need to do is work out a way to get the files out of there and then re-distribute them into folders instead of having every video all in one folder. It is also going to allow you to be more organized so you can find things more easily 1.
Try waiting a bit after opening the folder - it might just need some time to gather up all the data that you have stored in that signle folder. Wait for a maximum of 1 minutes or so. If it still hasn't loaded then there is no point in continuing to wait for it.2.
If the above did not work for you, then try disable or close any open programs/applications that you have running. Once everything is closed attempt to re-open the folder (give it a minute again).3.
If the above two suggestions did not work for you, packing it into a RAR file may work. TO do this you first need to download WinRAR (if you don't already have it), from here
. Once you have successfully downloaded WinRAR, install it and then navigate in Explorer to the folder but do not open it. Now right click on the folder containing the videos and then choose Add to archive... . A window will pop-up. Now if you have a huge hard drive, we will just need to pack the files and not actually compress them, but if you are running low on space then it would be wise to compress them so it fits - you can select how much compression you want to use by clicking on the drop down menu in the bottom-right corner labeled Compression method. Of course the more you decide to compress it, the longer the compression process will take. Now wait for it to be packed in an archive. Once it's packed you will notice a file called "Videos.rar" (The name could differ but you will know it's the right one if it has the ".rar" extension on it). Now open it, you will be in frotn of a file explorer looking into the contents of the videos folder. Select the files that you planned on deleting and right click on them and choose Delete Files. Sort out the videos - extract the videos to a certain folder (EG: Extract SpongebobSquarepants.mpg to a folder named Spongebob Movies). Once you have extracted each file, go back to where you extracted the files and you should now be able to access them without lag and have a bit of organization
Hope this has helped you - if you need more help or if my instructions were not completely clear just tell me and I will help you out