4 hours and 30 minutes is the same as 4*60+30=<<4*60+30=270>>270 minutes.
At 90 minutes per movie, Grandpa could watch a total of 270/90=<<270/90=3>>3 entire movies in 4 hours and 30 minutes.
On Wednesday, he watched 2*3=<<2*3=6>>6 movies.
Thus, during these two days, he could have watched as many as 3+6=<<3+6=9>>9 movies.
#### 9