Yes, he took those verses from the Sermon on the Mount (Matthew 5), as well as Mark, but he should have easily understood the Lord wasn't preaching self-slicing. Lust for women (not their wives) is a common affliction/sin of heterosexual men. The admonishment was to purge this sin nature from the inside through prayer and help of the Holy Spirit. Not to hack off body members... The Sermon on the Mount was to change the focus from the flesh and to expose our spiritual sins. I.e., lust for a woman not your wife being equivalent to adultery in God's eyes; anger against a brother without a cause being equivalent to murder, and so on...
So I understand Mr. Origen's Scriptural interpretation -- but he had to ignore the context of the Sermon on the Mount which exhorted the listener to focus on the Spiritual and less so on the flesh. One shouldn't rip Scripture out of its context.
The context is full of other extreme statements just like that one.