Important note (same as IRC Export): Same as Great HIT Export, you should ensure that this script runs before any preview/accept/hoard-type link-splitting/changing scripts in your Greasemonkey/Tampermonkey execution order. And if you have been using Preview and Accept MTurk HITs specifically, it may not work regardless of the execution order; if so, change to Cristo's Preview, Accept and Hoard and it should work.
Based on 'IRC Export (reformatted output mod)', I made this to export HIT information in multi-line plain text format, for saving in notes textfiles. It adds a button labeled 'TXT' next to each HIT title in an MTurk search results list, just like the 'vB' button added by the forum export script Great HIT Export (and the 'IRC' button added by the IRC export script). Note that GHE opens a display showing what you're copying and then you have to press ctrl+c yourself; this script (like the IRC export script) just copies the information to your clipboard directly after you click its button, and you should go paste it somewhere to see it. Update: as of v1.3c, Plaintext Export opens a dialog box like GHE's too!
I save copies of stuff like survey consent info as notes in text files, under a copy of the HIT info to know where it came, and this userscript saves time to not have to manually edit/adjust the formatting of the HIT info the way I had been. Most people don't do this much recordkeeping (though maybe this will inspire you to start? ;-) ) and so may not have much use/need for this, but here it is if anyone else wants it. Like some people have found with the IRC Export script, its output may be useful for other purposes too (it is Reddit-ready if anyone wants to use it there; there are two spaces at the end of each line, which tells Reddit to display the lines as separate lines instead of smushing them all together).
Here's an example of what the output looks like (ignore the line-wrapping):