How can one atone for watching bad videos, talking to strangers about shameful matters, and abandoning prayer, while desiring reconciliation from Allah?

You must repent to Allah the Almighty for your sins, and adhere to His law by performing the obligatory acts, refraining from the forbidden, and increasing in supererogatory acts. Safeguard your prayers, and stay away from watching what displeases Allah and speaking what does not satisfy Him.

What will help you with this is the continuous remembrance of Allah, supplicating to Him, and asking Him for steadfastness. Keep yourself occupied with what benefits you in your religion and worldly life. Continuously reflect on Allah's names and attributes, and be mindful of His constant awareness of you. Keep company with righteous women, seek sacred knowledge, and repeatedly repent whenever a sin occurs.