Hello! Our help will be more effective, if you copy and send us info about your browser and the Savefrom.Net extension:
http://en.savefrom.net/user.php?info=1
We'd also need some links you can't download (to test them).
For the better understanding it'll be great to see a screenshot with the error.
We are waiting for your reply, and thank you for contacting us Savefrom.net Team!

Hello, in order to help you better please, let me know me the name and version of your browser and version of the extension, all can be found using the following link: http://en.savefrom.net/user.php?info=1

Hello! Our help will be more effective, if you copy and send us info about your browser and the Savefrom.Net extension:
http://en.savefrom.net/user.php?info=1
We'd also need some links you can't download (to test them).
For the better understanding it'll be great to see a screenshot with the error.
We are waiting for your reply, and thank you for contacting us Savefrom.net Team!

Hi. Thanks for using our resources.

Hello. This was an error, which Savefrom.net has timely fixed. Now you can download a video regular way. We will consider your opinion, and will give our users a choice regarding this in the future.

Hello, Unfortunately, we don't fully understand you... please. provide us with more details regarding the issue.

Hello, 480p extension download only without a sound to download with sound you need to install the program Ummy Video Downloader: http://videodownloader.ummy.net

Hello, could you please send a few links you can't download. We will check it out.. 
For the better understanding it'll be great to see a screenshot with the error. 
We are waiting for your reply, and thank you for contacting us Savefrom.net Team!