This is not a total block but depending on your search query then google video search is blocked. A regular google video string is usually:
video.google.com/videosearch?hl=en&q=searchterm
Which is blocked! But moving the “hl=en” argument:
video.google.com/videosearch?q=searchterm&hl=en
Opens the result. This is most likely a blocking mistake and needs to be corrected (by unblocking of course).
Help unblock it by filling the form at internet.gov.sa, writing an email to unblock@internet.gov.sa or sending a fax to +966(1)2639290.