I have never been in this situation (but I will be in near future), so take the following with a grain of salt. I think employers see Coursera Certificate of Accomplishments not as a qualification that I know the topic inside out. But having a Certificate of Accomplishment to show for MOOCs that I took is a clear sign to potential employers that I'm willing to invest a lot of my free time to learn about new topics on my own. Which shows willingness to learn, being able to work independently on hard topics on my own under difficult circumstances (only help in the forum instead of having a tutor etc.). This is something that I think employers like.
> Do you avoid reading books for educational purposes or watching videos on professional topics because you don't get a certificate for doing so?
I read lots of books for educational purposes. But I read them because I'm deeply interested in the topic. I will probably never get any monetary gain from it (as I said: certificate or it did not happen). Videos on professional topics are rather uncommon in German culture (as I see it in opposite to the US-American culture). One reason for this is indeed that they don't deliver a certificate.