How to set the thumbnail of a video clip?

[mismgmt]

Hello- not a pro here, but just messing with various MP4 video clips. When clip is viewed by a file manager like Windows Explorer set to display thumbnails, a frame from the clip is shown. I can add or subtract frames at the beginning of the clip and a different thumbnail will be displayed in the file manager. Is there a way to nail down the thumbnail so the frame I want is used?

I Googled this question and didn't find anything but anguish and agony!

I am using an older Windows Movie Maker. I just realized it's been discontinued for some time. Is there an editor that has the capability of setting the thumbnail? Since I do this not too often, something free or cheap would be great.

I've also been taking tutorials on Creating a Cinemagraph in Photoshop on Lynda.com. Could I set the thumbs in this application?

Thanks!

[amaipaipai]

Hello- not a pro here, but just messing with various MP4 video clips. When clip is viewed by a file manager like Windows Explorer set to display thumbnails, a frame from the clip is shown. I can add or subtract frames at the beginning of the clip and a different thumbnail will be displayed in the file manager. Is there a way to nail down the thumbnail so the frame I want is used?

You can use any video editor to choose the frame you want and save it as png or jpg, use any photo editor to resize to 300x300 or anything close to that, anything bigger is overkill.

For command line you can use mp4v2, updated.
Add your thumbnais with the command:

mp4tags.exe -picture your_picture.jpg/png your_video.mp4

For a more easy approach, you can use any tag editor like Tagscanner, Mp3Tag, drag your video in it and add the thumbnail or change the tags you want.
Since I run command lines I rather prefer the mp4tags to do my own.