This is the 864th most frequent Estonian word.
vaata
"Vaata" means "look" or "see."
In this sentence, 'vaatamas' is an infinitive form indicating the action of watching, connected with the activity we were doing - going to the cinema.
Käisime eile kinos vaatamas uut filmi.
We went to the cinema to watch a new movie yesterday.
The word 'vaata' is used as an imperative form of the verb 'vaatama', meaning 'to look'. Here, it is a command to the listener to observe the specified object, in this case, the dog.
Vaata seda koera!
Look at that dog!
Here, 'vaatasid' is the past tense form of the verb 'vaatama', asking if the listener has observed or watched the mentioned show.