I have bolded most important parameters.
<iframe allowfullscreen frameBorder=0 src="https://snap.berkeley.edu/
embed?project=Beatles_glimmering_around_mouse
&user=kinestheticlearning
&editButton=true" width="480" height="370"></iframe>
It should not be multi-line (it only appears to be multi-line).
I have added an image that correctly shows everything in a single line, so click on the image below to see it in its full size:
It will produce what you see below: