Will Allah conceal the incident of being alone that occurred, despite my repentance, and could there have been surveillance cameras that filmed what happened, even though I am regretful and have repented to Allah?

There is no doubt that being lenient in interacting with a young man and being alone with him is forbidden and a temptation from Satan. However, if repentance is sincere, by abstaining from the sin, regretting it, and resolving not to return to it, then repentance erases what came before it, and "the one who repents from a sin is like one who has no sin." Therefore, one must remain steadfast in repentance, abide by Allah's limits, perform many righteous deeds, conceal the sin and not mention it to anyone, while having a good opinion of Allah and trusting that He conceals, forgives, and loves those who repent.