Sorting by video duration is a feature that was specifically requested by our paid members, so it’s available exclusively to them as part of the benefits they support the extension for. I don’t think that’s unfair or “scummy.” Premium features are clearly mentioned in the extension description, so there’s no attempt to hide this.

Furthermore, the decision to keep some features for the Patreon version of PocketTube was made to ensure the long-term feasibility of the free version.