Add platform support note and existing file handling documentation to README and skill docs, clarifying Windows 11-only testing, per-script ffmpeg/ffprobe requirements, and file replacement behavior with -y flag across Clone-Image.md, Clone-Video.md, Compare-Videos.md, Crop-Clips.md, Get-VideoAudio.md, SKILL.md and index.md

skill/Compare-Videos.md

@@ -429,6 +429,12 @@ For 3 and 4 videos, S2 (and S3/S4 as needed) are probed to verify all sources ar
 - **Pixel Format:** yuv420p
 - **Audio:** Copied from S1 (unless `-NoAudio` specified)
 
+## Existing Files
+
+- An existing `-Output` video is **replaced** without a prompt. ffmpeg runs with `-y`, so the old file is lost. Use `-WhatIf` first, or write to a new name.
+- The folder that contains `-Output` must already exist. The script stops with an error instead of creating it.
+- The source videos are only read and are never modified.
+
 ## Notes
 
 - Requires `ffmpeg` and `ffprobe` in system PATH