From here on, I assume that you already have a static version of the video playback working that does not involve Perl or webmin at all.

Your HTTP headers are very wonky. Please inspect them, again. Like I already told you, you should be using \r\n to delimit your HTTP headers.

The following lines are problematic:

print "Content-Length:  $end - $begin\n\n";
[download]

This means that for the web browser, all other headers after this get ignored.

Also, this means that your script outputs something like:

Content-Length:  50000000-0
[download]

... which is malformed. You will need to actually calculate the length before printing the length header.

You could have found these using the techniques I told you before. Maybe you want to retry these techniques.

yeah when i check the request and response header it is messing up here is the response header

Cache-Control: public, must-revalidate, max-age=0Pragma: no-cacheAccep
+t-Ranges: bytesContent-Length:  128959310 - 0
Connection: Keep-Alive
Content-Type: application/x-vlc-plugin
Date: Tue, 29 Dec 2015 11:17:01 GMT
Keep-Alive: timeout=5, max=100
Server: Apache/2.2.22 (Ubuntu)
[download]

yeah it is malformed..

The code you posted is Perl. "Standalone" in this context means just static HTML and Javascript, no Perl involved. This is intended for testing.