This probably comes from the yesterday's report made by COPE's sport sections, which said that the president of spanish refs is privately telling refs that video refereeing is coming soon. COPE's sport section isn't exactly the most trustworthy source (although it's not complete bs), so I would be skeptic about this... it could be that the refs have let this slip to COPE in order to pressure the spanish FA into introducing video technology.
You see, there are two sides here. La Liga and the refs want video assistance, but the spanish FA doesn't (and so it can't be implemented). La Liga wants it because they want to get a head start over other leagues... if they are the first big league to implement it then they'll get more attention, some people might start watching to see how it works, etc. The refs want it because they fear that FIFA won't call them for international games if they don't have experience with VAR... if the system is used in the 2018 WC and they've been officiating Liga games with it for a whole season before the event, then there's a good chance that spanish refs will have an important role in it.
Meanwhile the spanish FA has so far been adamant about not implementing this. I don't think they've ever given a reason for it, but it might have to do with it not being available to smaller competitions and clubs, idk. In any case, they've been in war with La Liga for years... the presidents of La Liga and the spanish FA absolutely hate each other. Both institutions constantly fight and it's possible that the FA is just going to say "no" to anything La Liga proposes, unless they really have to comply.