Firefox's update + YouTube's SPF scripts kill TabMixPlus' open-in-new-tab functionality on YT.

I just spent two hours trying to figure out the solution to this problem.. and fixed it, so I came here to share it with others who may have the same issue.

Between Firefox's latest update and YouTube's SPF scripts, the functionality of TabMixPlus was broken. Despite having the settings direct all links, including Javascript links, to open in a new tab.. YouTube would ignore this and open videos in the current tab, when left clicked.

I managed to track down the aberrant behavior to their SPF scripts, specifically, when you click on a video in your Subscriptions page, Watch Later or Search Results, YouTube would grab control of the current tab with a link that ended in &spf=navigate. (I found this through Ublock's logger.)

To restore TMP's functionality to force all links, including YT video links, to open in a new tab and not steal and transform the current tab, the following filter can be used.

youtube.com##script:contains(navigate)