Manually added videos will always feature a 'circled plus' in the video thumbnail in MyVideoly. 

We ensure  that only  embeddable videos available on YouTube are displayed in the widget. We also perform this check on videos that you manually add via MyVideoly.

If a video you have added cannot be embedded, or is not available on YouTube, you will see a notification of this in a green thumbnail (see example below) 

Read more about managing video content in MyVideoly.