Why is youtube delivering files in 2mb size instead of the whole 50mb. Unable to down

[enggr]

I am a big user of Replay Media catcher 4 and I use it to download legal free videos of youtube for offline watching as well as to avoid buffering. I use it to transfer files to my android device and watch it on as well.
The 15 minute videos that gets legally uploaded by news sites (eg: below) use to download properly as a single 50mb file until few days ago. Nowadays when I have replay media catcher open in recording mode and open a youtube video its downloading several pieces of file in the size of 1.6 mb or 2.3mb (10 files or 15 files total for just one video).
This pretty much makes offline viewing impossible and useless as I am not getting the whole 15 minute file.
Some days i get the file as a whole.
Is youtube delivering the video files as pieces to reduce bandwidth?
How do I get the file as a whole? Is there a workaround? I use orbit downloader sometimes and for the files under question they show the files as 2.3mb size as well.
Please help me in downloading the file as a whole. Thanks in advance