Weird Material and Crack on Floor

I removed the carpet (including the paddings and tack strips) today. I have two questions.


https://www.dropbox.com/sh/bm3olcdti...qe8csVkWa?dl=0


First picture, upon removing the carpet, I noticed a yellow paper-like material on the floor. It breaks when scraped. It is not paint and it is not the gel (adhesive) that is in the picture that I am referring to. This is not my first time that I have seen this type of material. It was at another house. The guy who did my floor at that house told me, not to be bother with it and tile can be set on top of it. He told me it is some type of tile (earthquake) proof material.

We were skeptical of his advise and concern that he was trying to take a shortcut so we scraped it off anyway. It took a long time because there was adhesive underneath it. Eventually, it did come off.

Can someone tell me more about this material and can tile be set on top of it or should I scrape it off?


Second picture, there is a crack that runs across the bedroom. The same floor guy told me not to worry about it because that is normal in old homes (1990). Should I repair the crack and how? Or is it safe to just tile on top of it?


Thanks

 

Looks to me like old adhesive that has dried out. It can become hard on top but still be a little gooey underneath.

 

Should I tile just on top of it? And do you have any thoughts on crack in the room for the second question?

Thanks MarkSR