Reinstall the extension, remove Chameleon.

Install the Tampermonkey extension and the Savefrom script in it.

Install the extension here in these links.
Google Chrome. First 1 then 2.
1. Tampermonkey black: https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo?hl=en
2. Savefrom.Net: https://download.sf-helper.com/chrome/helper.user.js?ts=1455972944179

Hello, in which format are you downloading?

For the better understanding it'll be great to see a screenshot with the error.

Send a couple of links to files that you can not download.

Hello, Subtitles can only be downloaded if they are connected to a video and not created automatically.
You can download them via: http://en.savefrom.net or SaveFrom.net Helper (extension).
Subtitles can be downloaded in an xml format.

Please reinstall the extension:

https://download.sf-helper.com/safari/helper_last.safariextz?ts=1529315476602

We checked the video, they are downloaded.

Hello, unfortunately not, we can not help you with this.

Hello, Could you please send a few links you can't download. We will check it out.

Do you download via the extension SaveFrom.net Helper or the website SaveFrom.net?

Please, send me the information listed here: http://en.savefrom.net/user.php?info=1

Hello, send a couple of links to the files that you can not download "for the test."

Hello, in order to download MP3 from Youtube you need to install our program Ummy Video Downloader,
Also with the help of it you can download videos in high quality with sound: https://videodownloader.ummy.net

Hello, unfortunately not.

Hello, please, send us more details regarding the problem.

For the better understanding it'll be great to see a screenshot with the error.