The TV shows come from the archives of American network CBS and are available to watch only in the US, so if you're reading this outside the States, you're out of luck.
Those able to get hold of the new content will find a small selection of old dramas marked with a special 'full-length' logo, including Star Trek (the original series), Beverly Hills 90210 (ditto) and The Young and the Restless.
The official YouTube blog explained the move: "As we test this new format, we also want to ensure that our partners have more options when it comes to advertising on their full-length TV shows.
"You may see in-stream video ads (including pre-, mid- and post-rolls) embedded in some of these episodes; this advertising format will only appear on premium content where you are most comfortable seeing such ads."
Whether or not such mouldy old content will be enough to persuade the TiVo generation to sit through ads remains to be seen, but we're glad to see the YouTube guys at least being upfront about it.
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J Mark Lytle was an International Editor for TechRadar, based out of Tokyo, who now works as a Script Editor, Consultant at NHK, the Japan Broadcasting Corporation. Writer, multi-platform journalist, all-round editorial and PR consultant with many years' experience as a professional writer, their bylines include CNN, Snap Media and IDG.