YouTube/Twitch Enhancer by 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, words, phrases, or /regex/ patterns. Dodge spoilers, reaction content, or topics you are done with.
Remove Shorts everywhere: shelves, tabs, the sidebar entry, and open /shorts links in the normal player.
Hide already-watched videos past a progress threshold, with per-surface control (Home, Subscriptions, Search, Related, Channel pages, Playlists).
Extras: clutter removal (ads, promos, Mixes, news shelves), auto max quality, in-player volume boost to 500%, and a cinema mode that darkens everything around the player.

TWITCH
Block channels, whole categories, and title keywords from the front page, directory, search, and sidebar. 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.
Third-party emotes: see BetterTTV, FrankerFaceZ, and 7TV emotes in chat, with a searchable emote picker.
Player tools: pin source quality, in-player volume boost, cinema mode, and one-click clip sharing to chat. Download clips as MP4.
Chat options: hide chat, join anonymously, plus performance tweaks (line limit, message batching, smooth scroll).
Hide the auto-playing front-page carousel.

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. The only network requests are the optional third-party emote lookups (BetterTTV, FrankerFaceZ, 7TV), which you can turn off.