YouTube/Twitch Enhancer — C4rcer

Take back and level up both YouTube and Twitch, all locally in your browser.

YOUTUBE
Block entire channels: right-click any video, use the injected item in the video's 3-dot menu, or add channels by handle, URL, or name. Every upload disappears from home, search, subscriptions, the sidebar, and end-screen suggestions.
Hide videos by title keyword and comments by comment keyword: words, phrases, or /regex/ patterns.
Remove Shorts everywhere, and hide already-watched videos past a progress threshold with per-surface control (Home, Subscriptions, Search, Related, Channel pages, Playlists).
Player tools: default playback speed with [ and ] hotkeys and optional per-channel memory, audio compressor for quiet dialogue, A-B loop, frame screenshots, volume boost to 500%, auto max quality, and cinema mode.
Never pause me: automatically dismisses the "Video paused. Continue watching?" prompt. Optional: keep autoplay off and auto-expand the description.
Opt-in community data (all off by default): SponsorBlock auto-skips sponsors and other crowdsourced segments with per-category control and progress-bar markers; DeArrow replaces clickbait titles and thumbnails with community-chosen ones; Return YouTube Dislike restores the dislike count. One add-on instead of four.
Extras: clutter removal (ads, promos, Mixes, news shelves, members-only videos).

TWITCH
Block channels, whole categories, tags, and title keywords, and hide reruns. No more content you never asked to see.
Auto-claim channel points, drops, and Moments. Drops are claimed for you in the background without interrupting the stream you are watching.
Chat: BetterTTV, FrankerFaceZ, and 7TV emotes with a searchable picker and Tab-completion, keyword highlighting, word/user blacklists, alternating line shading, show deleted messages, anonymous mode, and performance tools for busy chats.
Player tools: pin source quality, volume boost, audio compressor, cinema mode, screenshots, stream uptime display, speed hotkeys on VODs and clips, one-click clip sharing to chat, and clip downloads as MP4.
Sidebar hover previews show a live stream thumbnail, and the auto-playing front-page carousel can be hidden.

Stay in control: every block has an Undo, an audit mode shows exactly what is hidden, and a master switch pauses each side instantly. Works on Firefox for Android too.

Private by design: everything runs locally, with no accounts and no servers run by this add-on. Optional features that talk to community services are clearly labelled and easy to turn off: emote lookups (BetterTTV, FrankerFaceZ, 7TV), SponsorBlock (only a hashed video-ID prefix is sent, never the video ID itself), DeArrow, and Return YouTube Dislike.

Credits: segment, title and thumbnail data by SponsorBlock and DeArrow (https://sponsor.ajay.app, data licensed CC BY-NC-SA 4.0, by Ajay Ramachandran and contributors); dislike counts by Return YouTube Dislike (https://returnyoutubedislike.com). This add-on is not affiliated with those projects; please consider supporting them.