[ACK] WebCache files keep increasing

I am having a problem with the videos in the media collection downloading files into the Logos 4/Data/**********WebCache folder. After I have watched the entire video for the  first time, the file associated with that particular video is a certain size, but when the I go back at a later date to re-watch that video, the file for that particular video increases.

Example: Basics of Biblical Hebrew Video Lectures
The video Introduction to Basic of Biblical Hebrew video lectures file name pdhbgnej.jag
The fist time I watched the complete video the file size was 175,953 Kb
The second time I watched the complete video the file size was 351,905 Kb
The third time I watched the complete video the file size was 527,857 Kb

The Video Lesson the Hebrew Alphabet
The fist time I watched the complete video the file size was 1,161,867 Kb
The second time I watched the complete video the file size was 2,323,734 Kb

I checked and found this happening on DIY Bible Study Videos and also on Basics of Biblical Greek Video Lectures. I have not checked if this happening with any other videos

I looked at these on my other computer and found the same thing is happening.

I am running Logos 6.4 Beta 1 (6.4.0.0006)

Is this a bug or glitch in the program or is this the way it is suppose to happen. I fear that if kept watching these videos my hard drive will be filled with Web Cache files.