How do you Paste Album Art from iTunes?

This is about tracks that I own in iTunes. When I right-click on the album art in iTunes and select COPY, and then paste it into the thumbnail image in Mp3tag, the art appears to be a PNG file. (What I paste it into Windows Explorer it creates a BMP file, which further confuses me.) I have a feeling that PNG files embedded into MP3s will cause problems downstream, so is there an easy way to convert it into a JPG before pasting or within Mp3Tag?

Try this version