Iker Losada put Betis ahead before Marcus Rashford, Amad and Casemiro had United 3-1 ahead before Diego Llorente struck the final goal of this preseason friendly.
Ten Hag later said: "I think it was okay, the lads did well. At the start we had some problems in getting control and we went 1-0 down which shouldn't happen. I actually think this was the first time they entered our box. But then we took over and we bounced back, I think we made three really good goals, first the penalty and it was a good action from Amad.
"The second I would say is a very good goal. The third one from the corner is also a nice goal. The second where Harry Amass put the cross and Amad scored the goal with the finish was lovely.
"Yes, he (Amad) is performing well and a good pre-season so far. You could see absolutely he is making an uplift in his game. Also in the defending part with the counter-press but also with the pressing he is doing really well. So I am really pleased with his performance."
"This week everyone has to get more minutes in to come to match fitness. Of course the games will get tougher and I think on Saturday it will be a very good test when we face Liverpool. That is very good preparation for the new season.
"What we want to achieve is we want to be very proactive and very aggressive and it doesn't matter if sometimes we are high or sometimes in a lower block. We have to be very aggressive and in order to get this we need to start the press at certain points and all be on one page. Then the intensity must convert to being with the ball and we must do this as a team."