Why was the Holy Spirit poured out on the Jewish believers in Acts?
The Holy Spirit's outpouring on Jewish believers in Acts served to supply more signs, miracles, and wonders that would convince Israel. This was so they could continue to see the nation of Israel converted to faith in their rejected Messiah, not yet to evangelize the whole world.
Les teaches that the only way to convince them was more signs, miracles, and wonders. Therefore the Holy Spirit was poured out upon these Jewish believers so they could continue to see the nation of Israel converted to faith in their rejected Messiah. At that point, Les explains, they were not yet concerned about evangelizing the whole world; their chief concern was the nation of Israel, because Israel had to be converted to the Last Man. He then points to Acts 3:19, where Peter says repent and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord. The semicolon, not a period, carries the thought into verse 20: Israel converted, and the times of refreshing shall come from the presence of the Lord. Then God will send Jesus Christ, whose remaining purpose is to be the King.