Issue Summary There is a critical data-wasting bug in YouTube's ad-injection logic on desktop browsers. While the player successfully pre-buffers video data ahead of time, it completely flushes and destroys the entire local video cache the moment a mid-roll advertisement interrupts playback. Once the ad finishes, the player is forced to re-download the exact same video segments it already fetched, causing massive, redundant internet data usage.

Environment & Device Details Platform: Desktop Web Browser

Browser: Google Chrome (Latest Version)

Operating System: Windows / macOS / Linux

Steps to Reproduce Open a long video on YouTube using Google Chrome.

Observe the light gray buffering bar advance far ahead of the current playback time (indicating a healthy local cache).

Allow the video to play until an automated mid-roll advertisement triggers.

Watch the ad complete (or click "Skip Ad").

Observe the Bug: As the main video resumes, the light gray buffering bar instantly drops back to zero. The player is forced to restart network requests to fetch the upcoming video data all over again.

Technical Verification (For Advanced Users) You can visually confirm this data drain in real-time:

Press F12 to open Chrome Developer Tools and go to the Network tab.

Filter by Media or look for videoplayback requests.

Note the size of the downloaded segments before the ad.

Once the ad finishes, you will see Chrome duplicate those exact network requests to re-fetch the video timeline you just downloaded.

Expected Result The video player should isolate the main video's cache from the ad-stream. The pre-buffered segments should remain stored in the browser's temporary RAM/cache so playback resumes instantly without pulling extra network data.

Actual Result (The Bug) The player triggers a hard reset of the buffer timeline upon ad execution. For users on metered connection plans, capped Wi-Fi networks, or mobile hotspots, this flaw forces them to pay for the exact same video data multiple times over.