In this video the speaker Rohit Arya says at 1:21 minutes that sex if used 'correctly' can boost one's Sadhana
- Is there any scriptural evidence to support his statement?
- What can possibly be the correct way of performing sexual intercourse?
Is there any scriptural evidence to support his statement?
Yes it has a scriptural support
Her lap is the sacrificial altar, her hair the sacrificial grass, her skin within the organ the lighted fire; the two labia of the vulva are the two stones of the soma-press.
He who, knowing this, practices sexual intercourse wins as great a world as is won through the Vājapeya sacrifice; he acquires for himself the fruit of the good deeds of the woman. But he who, without knowing this, practices sexual intercourse turns over to the woman his own good deeds.(Bṛhadāraṇyaka Upaniṣad 6:4:3-4)
I will update my answer soon