Hello, Thanks for contacting Savefrom.Net Support.
We can make our support more effective if you provide us information about your browser and extension.
You can find out this information on this page: http://en.savefrom.net/user.php?info=1

Please, send us links for files, which can't be downloaded.

Hello, We need some more details to be able to solve this issue.
Can you please send the information about your browser and current extension.
It all can be found here: http://en.savefrom.net/user.php?info=1

Please, send us links for files, which can't be downloaded.

Hello, please give us more details.

Thank you for using our extension SaveFrom.net Helper

Hello, and you have an extension does not work on Safari 10?

You wrote:

(Hello, thanks for quick response. after delete and reinstall to the 6.70 version (Tampermonkey 4.1.10 with helper.user.js), plus little tweak in the setting (download mode: browser API), now I'm able to get proper file name.(coming from the video title itself) However, this will work only when I directly download the file from Chrome. But I still get the unproper file name when downloading via download manager (Folx GO+).)
The problem in your download manager.

Hello, in order to help you better I need the following information.
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

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

Hello, Reinstall the extension after an older version is uninstalled. The current version is 6.70:

http://en.savefrom.net/user.php#helper_install

If you upload a video via the browser in the video name correct?
The fact that you load another boot loader and you have the wrong name, we can not help here.