Generate AI YouTube comments and replies from a video URL using GPT-4 and Google Sheets

How it works - A form trigger accepts any YouTube URL: youtube.com/watch?v=ID, youtu.be/ID, youtube.com/embed/ID, or just a plain video ID - A code node normalises the URL and extracts a clean video ID for the YouTube Data API v3 - Calls the API to fetch video stats (title, description, tags, views, likes, comment count) - Fetches comments from the videos commentThreads endpoint, capped by the form's Max Comments to Process field - Flattens each comment into its own item, then merges two ranked lists deduped by commentId: the 5 newest comments by publishedAt and the 5 highest-engagement comments by likes plus replies - A GPT-4 agent writes a natural, human-sounding reply for each top comment, responding as a fellow viewer (not as the channel owner) - In parallel, a second GPT-4 agent writes one original top-level comment based on the videos title and description - A structured output parser guarantees clean JSON for both agents - Replies are merged with the top-level comment by videoId, normalised into row shape, and appended to Google Sheets - one row per reply Set up steps - Setup takes about 5 to 10 minutes - Connect a YouTube Data API OAuth2 credential (used by both the Get Video Statistics and Get Video Comments nodes) - Connect an OpenAI API credential (defaults to gpt-4.1-mini; swap to any model you prefer) - Connect a Google Sheets OAuth2 credential and pick your destination spreadsheet plus tab in the Save to Google Sheets node - Create a tab with these column headers in row 1: videoId, videoUrl, videoTitle, commentAuthor, commentText, myReply, myVideoComment, selectionType, videoTags, viewCount, engagementScore, videoDescription, likeCount, commentCount - Optional: tweak the system prompts inside each AI agent to match your niche, voice, and brand - Submit a YouTube URL via the form trigger to test - Detailed per-step notes live inside the workflow as sticky notes