I have the DownloadHelper in Mozilla and Internet Explorer. With that extension I can download *.flv videos from a web (not youtube). But I discovered that when I play the video that I downloaded, the quality is not the same as the original video. I lose quality. The only way to download the videos that I want is via DownloadHelper. I tried with the convert option to different formats and I cant get the same quality as in the original web page. Why? I dont know. Maybe is a codec thing? or I need to do something special? please give me your opinion. Thank you.
If your downloading the FLV files, then you are getting the source. Download helper doesn't transcode. Sometimes you will have multiple resolutions to choose from. The default download may not be the highest available or the one your watching on the page.
This is often true of youtube, for example