[DTV]

If it was the previous week's edition played by mistake it would make more sense than one from 6 years ago,

Not really, depends on how they're listed in the system. If you're searching for Newswatch_22_09_20..., it's more likely to get an edition from 2017 than last week. Like you, the producer might have assumed that older versions would be archived, so would think nothing of selecting the first 22nd September edition that popped up. There's also a chance that yesterday's edition might have been incorrectly labelled, so that was the only 22nd September edition that was on the system.