Securing furniture to prevent tipping due to earthquakes and babies
The velcro type product you posted looks like it has adhesive on both sides.  The velcro itself would probably be plenty strong if the straps are large enough, but I suspect that adhesive on the wall would not work out well.  It could fail too easily by simply ripping the top layer of paint off.  Or, when you do want to move you are going to rip a big chunk of paint (or more) off the wall when you try and remove it.

A screw into a stud is going to provide the most secure hold.  I usually use 2 1/2" #8 screws for this purpose. You can either get metal brackets or the purpose-made earthquake straps at the hardware store.  If the bookcase is made of particleboard and/or it's heavy, then I would consider two brackets/straps to hold it since the connection into the top of the bookcase will be much weaker than the connection into the wall.  

A few holes from #8 screws will leave holes considered "normal wear and tear" in California.  If you (or your landlord) are really particular, it will be easy to patch when you are moving out.