Totally worked for me!

I was looking quiet some time for an add-on like this, and then found it by chance. Works without problems.

Amazing addon, no more confirming same type of file downloads over and over.

The only inline disposition addon I've found that works with FF57, and so far it seems to work great.

Finally I found it! It works with .torrent files and this is what I needed most!

Elated to find this replacement for the Inline Disposition addon that apparently was updated for 57, but simply does not work. Thank you so much!

Avast is warning that this is a unreputable browser addon. I have no idea how they make this decision, though it might be worth looking into.

I've had no problems with the extension otherwise. Great addon.

Firefox's handling of the "content-disposition: attachment" header can be quite confusing, to put it mildly. There's a bug report about this that's nine (!) years old (https://bugzilla.mozilla.org/show_bug.cgi?id=453455) and that's still open and unassigned.

The Inline Disposition 2 extension used to fix this quite nicely, but with Firefox Quantum that's no longer an option. Since upgrading to Firefox 57 I've tried a couple of WebExtensions to get rid of those unnerving "Always do this from now on (haha, just kidding, still enjoying your Chinese water torture?)" messages, but none of those really worked for me, including this one.

So what I wrote earlier about the "Display inline" extension is also mostly true for "Bypass Forced Download": Nicely done with a simple interface and very well-documented, but it doesn't seem to work everywhere. For example the .torrent files on http://hdreactor.info/ are still delivered as attachments with this extension active. Lukas, maybe you want to have look at this issue? I'd file a bug report but you don't seem to have a github or similar site.

EDIT: I've now replaced this extension with Header Editor (https://addons.mozilla.org/en-US/firefox/addon/header-editor/), a more generalized extension where I could quite easily define a rule to ignore those those pesky Content-Disposition: attachment headers on any website, including the one mentioned above.

Actually a working addon for FF 57+ which fixes non-working "always do it files of this type" bug.