I would even say they're only a little similar if you're not familiar with neither Greek nor any of the Romance-branch languages.
I worked with a bunch of "malakas" from Greece ;) and it really is quite uniquelly sounding for somebody who can speak a bunch of other European languages (the only language I ever confused with it was Finnish and it still sounded not-quite-it).
I'm sorry, I acknowledge that it isn't just you but I really don't hear it. The cadence and how the syllables are accented are all off, as are many of the letter sounds. I could see maybe Portuguese? Like yeah, it does sound vaguely romance language, but not very Spanish IMO.
Edit: watching more of the video I can kinda see why people feel that way, listening to individual words can sound similar, but the cadence is very different and the consonants sound more "Eastern European" to me if that makes sense. Heck even many of the vowels, while definitely the same sound, are different enough to sound wrong. Also Greek sounds much more "choppy" and Spanish more smooth to me.