Sometimes file names with white spaces causes issue.
Try removing the spaces in filename i.e, try renaming files like
ChellaSoftwarewithvoiceover.mpg
ChellaSoftwarewithvoiceover.ogg
and then modify the source accordingly
<video width="320" height="240" controls="">
<source src="C:\chella\ChellaSoftwarewithvoiceover.mpg" type="video/mpg">
<source src="C:\chella\ChellaSoftwarewithvoiceover.ogg" type="video/ogg">
Your browser does not support the video tag.
</source></source></video>
Hope, it helps :)