I hope I'm not coming across as mean, but it's not great. There's too much going on, the colors are muddled, the font and color of the text make it very hard to read and the most readable thing on the thumbnail is your name, which shouldn't be on your thumbnail anyway.
A thumbnail should tell you what the video is about. Use a simple background with one or two pictures, use a more simple font with an outline and take your name off the thumbnail. Bright, simple and readable are the three key words when it comes to thumbnails!