MyThumbTester guide
Keep a downloaded YouTube thumbnail and preview PNG as a review record
Save an available public thumbnail and a MyThumbTester PNG export together to record the exact local layout and title you reviewed.
Save the source image and the selected preview because they record different things
Keep both the public thumbnail image you selected in MyThumbTester’s downloader and the PNG you export from the tester. The downloaded JPG records the available public image response you chose. The tester’s Download PNG button exports the currently rendered canvas with a filename based on the selected layout, so it records the local illustrative placement, title, metadata, and theme at the moment of export. This is a reproducible browser-local workflow, not a prediction of click-through rate, ranking, distribution, or views.
Together, those two files let you revisit what you actually reviewed instead of relying on memory. They do not establish ownership of the public image or prove how a third-party platform will present it.
Start with one available public image
Enter a public YouTube URL or 11-character video ID in the downloader. It lists only thumbnail image responses that the browser can load, and their available sizes can vary by video. Choose one listed option to download as a JPG, or send it directly into the tester before making the preview export.
The downloader handles public thumbnail images only. It does not download a video, keep a hosted copy of the image, or create a missing size.
Export the layout you actually checked
In MyThumbTester, select the layout you reviewed, enter the exact title and optional metadata, and use Download PNG. The implementation renders the selected layout to its canvas and creates a local PNG named thumbnail-tester followed by the current layout name. If you reviewed more than one layout, export each one separately rather than treating one export as a record of all six.
Store the source JPG and each review PNG together with a short note such as the video ID, image size shown by the downloader, layout, and the visible change you decided to make. This note is for your own visual review process, not an A/B test result.
What a saved review record cannot tell you
A JPG and PNG pair cannot confirm reuse rights, guarantee future availability of the public image, show how every platform will crop it, or demonstrate which thumbnail will earn more clicks, rankings, distribution, or views. It gives you an auditable record of one local image-and-layout inspection; real platform data is still needed for performance questions.