I click on the rotating balls of download helper and it looks as though the download is taking only a couple seconds. Then, when I click on it to play it it doesn't work and says, The document “Barney_ I Hear Music Everywhere.mp4” could not be opened. The movie's file format isn't recognized. To see if additional software is available that will enable QuickTime Player to open the movie, click Tell Me More.
I have a 2011 Apple Macbook Pro 13".
Any help is greatly appreciated.
Please update Firefox by going to Help > About Firefox and follow the instructions.
Also make sure you got the latest version of Download helper from addons.mozilla.org.
Can you download and save the files directly?
There are a lot of video players available that can play those videos directly without conversion.
A few days ago I noticed that the Download Helper extension wasn't able to save files that were retrieved with a ratebypass parameter and I got files with a 0 bytes size (throttling still worked, but of course slow with around 70 KB/sec).
It seems to working now again, so I assume that is was a problem on the Google servers
It is now 16 August 2012. These symptoms are still happening for me.
It is quite possible this is a problem on Google/YouTube's end. They have been catching a lot of flak for copyright violations and maybe they have decided to clamp down.
I use download helper A LOT, so I hope this isn't the end. I'm at Firefox version 14.0.1 and Download Helper 4.9.9 so pretty up to date, I think.
Video DownloadHelper currently works for me in the Firefox 15 beta version that I've installed it in.
It had stopped working some time ago and gave files with 0 bytes size, but started working again a few days later, so that may have been an issue on the YouTube side with ratebypass (loading at maximum speed) as opposed to throttling (loading with the speed that the player needs).
Did you try to clear the YouTube cookies and maybe clear the cache?
Also make sure that you aren't blocking any (ad) content in case YouTube is detecting that.
I have had the problem of download helper downloading a file too small for the size/length of the video and no matter what video I am download the size is always 2400 KBs. and the file when double clicked open my player but nothing plays.
I have fixed it somewhat by clicking on the YouTube icon in the lower right corner of the window (when mouse pointer is over YouTube "tube" is red and
white and I get a "Watch on YouTube"). Clicking on this takes me to YouTube and the video. Then back up at the address bar and the download helper red-blue-yellow rotating balls click on the down arrow net to the balls.
I get may more options - frame rates etc. then move pointer to the frame
rate you want when it turns(highlights blue with arrow on the right) you get a box with download options - download & convert, Quick download, and download - I click download. It downloads a file of the correct size that I am able to play.
It is a .flv file. So, I have to play it on a flv play or convert it to the format
that I want. I us VLC Media Player (free open source http://www.videolan.org/ donate if you us it) it will convert some formats too.
I have also gone to tools>add-ons>and at download helper 4.9.9 to the
right click the "option" button which bring up the Preferences box and along tab at the top click on Conversions then I unchecked the box
Conversion enabled. Also, I have removed the plugin clea.nr (http://clea.nr/blog/). I am not
sure if it caused a problem. But, my not being able to download and save videos seemed to start about the time I installed this plugin. I am sure YouTube is not happy when a plugin that cleans up - removes all the advertising. At least now I am again able to download save videos.
I tried the advice of deleting YouTube cookies. This totally WORKED for me. I don't understand this, so if anyone can explain the theory, that would be great.
Firefox has a tool that allows you to delete cookies one by one. I took out about a dozen of them, which I found under two different names. Probably only one of them was the critical one. But that's how it goes with this type of problem.
upgrade, Upgrade, UPGRADE!
And every time something quits working right.
F*** FIREFOX AND THE INTERNET!!! After all it won't be long now before the Internet is shut down or you will need a license to get log on.