On LG TVs, Crackle is available as an app download, no need for Plex to carry it in the Movies & TV section for, at least, LG products.
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But I write because the volume of Crackle’s commercials (ads) is much higher than the volume of Movie & TV content. One add in particular, by Monster Energy Drink, is 20 db louder than even the other commercials. WARNING: if you are watching Crackle via your expensive home theater system, a Crackle ad could damage your speakers! I estimate my speakers received a jolt of 300+ watts last night before I could react. I’ve only heard tweeters breakup like this when I accidentally removed a cable with power applied.
Plex, if what you say is true, the new WB, Lions Gate, etc. content is buried among other titles in the Crackle channel; then there’s no way of knowing how to avoid Crackle… unless all Plex Movies & TV are avoided.