can you guys tell me the best as well as the simple modules for flash and youtube to do this task?

No.

• Go to CPAN and search for youtube
• then pick one :) say WebService::GData::YouTube
• install module  cpanp i WebService::GData::YouTube

Repeat!

• Go to CPAN and search for open browser
• then pick one :) say Browser::Open
• install module  cpanp i Browser::Open

Now read the SYNOPSIS, copy/paste some bits, ... and you're programming

See also get-flash-videos https://github.com/monsieurvideo/get-flash-videos/blob/master/lib/FlashVideo/Site/Youtube.pm