From Dennis Preston yesterday, a report from the Twitterverse on Wednsday (10/1), in which:
Apparently a Grand Jury member in the Ferguson [MO] shooting put up a message which suggested outside contact and immediately took it down. But not before somebody “screenshotted” it.
Within seconds of posting this, her friends told her to delete it and she did. It was screenshotted first.
Start with the N + N compound screenshot. Then verb it (convert it directly to a verb), to get to screenshot, which will then be inflected regularly, to give PST/PSP screenshotted.