Updated Sept. 2024.
NicoNico, a big name in Japan for video sharing, created a live chat that lets viewers post comments that scroll across the screen live. This makes watching videos more interactive and fun. It turns watching into an active experience, mixing passive watching with active chatting.
You can now enjoy a similar experience with a browser extension called Flow Chat for Youtube Live.
The chat flows smoothly and beautifully on the screen, with different colors representing various roles such as guest, member, moderator, owner, and yourself. Additionally, you can customize the text to suit your preferences by adjusting the size, duration of visibility, and outline thickness.
One of the best things from this flow style is that you can watch live streams in fullscreen while still keeping an eye on the chat. This means you can immerse yourself in the content without missing out on the discussions happening in real-time.
Download from Chrome Web Store:
Unfortunately as of Sept 2024, I couldn't find one for Firefox, but there is likely a similar extension available like Danmaku Chat.
Read also: LiveTL: Translate Youtube Live Chat in real time