Amplifying audio in a video

I presume your flip camcorder records to mpeg4.
Audacity is a free and easy to use program to edit audio.

How to amplify audio with Audacity:
http://www.recipester.org/Recipe:Amplify_Audio_with_Audacity_19352851

but that is for audio....i am talking about audio that is in a video....

How to Import audio files into Audacity:
http://www.recipester.org/Recipe:Import_audio_files_into_Audacity_21858738
Also see:
http://www.divx-digest.com/articles/normalize_avi.html

are yousaying i need to remove the audio frst then edt

Any camera has an inbuilt mic, if the recording volume is very low first check the manual if there is any settings to increase the volume in the recording, dont be too far away from your subject since it records in mono if using the older version
these have  automatic gain, digital zoom, monaural sound< not stereo
There is several versions to this flip camcorder, which do you have?
Mino HD or Ultra HD
the newer versions offer 2 microphones for stereo. Hense increasing your sound volume I dare say
http://www.fastcompany.com/blog/noah-robischon/editors-desk/flip-digitals-ultrahd-camcorder

All Flip camcorders record at 1280 x 720 resolution using H.264 video compression, AAC audio compression and the MP4 file format as of September 20, 2010
http://en.wikipedia.org/wiki/Flip_Video

You could play the clip and capture it with increased volume
Try VLC it is priceless for all the inbuilt tools it supports,  play and records  / converts http://www.videohelp.com/tools/VLC_media_player
http://www.videolan.org/vlc/download-windows.html

hey viki does that program allow you to make the audio i your video sound louder?

yes, up to 500% once, but you can repeat
page 121 ftp://ftp.corel.com/pub/documentation/manuals/Corel%20VideoStudio%20Pro%20X3.pdf