Madmeg Having suffered at the hands of a criminal builder who has left my house almost uninhabitable, I have some experience of the "Hoarder" situation because I have had to live with things in boxes all round me waiting for damaged floors to be taken up and other serious problems to be addressed. Because I have had to keep my items normally kept in cupboards, in boxes, I was accused of "Hoarding" by my children but when I asked for help from the professional people who clear hoarded types of houses, the lady immediately on entering said "this is not hoarding! You are having work done! Look you have labelled the boxes! Also it is very clean." However, prior to her lovely words, I felt almost suicidal when my children tried to make me throw away my dinner service etc. because I could not put it away until the building work is done. I shall never forget how I felt when they decided to treat me like this and not see me as I really am and what has actually happened to me.
So, I have learned a lot about being treated as a Hoarder. I tried to learn a lot about how to organise a house too by going on YouTube, because I have no cupboards etc at this time. As for being treated as if I lived with things in boxes around me on purpose, I learned that it is extremely demeaning, painful, and intolerable to the point that you want to die! You feel that those who should understand are the ones who are being the most judgemental, cruel and selfish. You feel they do not care about you and do not see you as the person you really are.
You must act with the softest and gentlest of kid gloves. These are his rooms. These are his things. They are not making him ill as far as I can tell. They are not causing the walls of the house to explode or the floors to fall in. (My floors had wet rot because neighbours have covered my damp course and air bricks).
As for keeping broken electrical things, he cannot believe that he will not mend the items one day. I am nearly his age. I was brought up never to throw away something expensive (especially electrical as they are expensive) without trying to fix it. He and I are post-war babies born when rationing was still in place. I still tear up old sheets for floor cloths and napkins. We feel we might cause a terrible problem if we throw away something we ought to re-use. So we decide we shall mend it. Then we find, we have arthritis, time rushes by, the jobs pile up.... Being old and not being able to get things done is horrible. Being told you can't do things makes you feel worthless, unloved, no use, disrespected and a waste of everyone's time.
As for the video tapes and machines like the printer that doesn't work, I would try and find somewhere to put up shelves on which you can store these. Possibly the garage or a dry shed. I suspect taking them to the recycling centre would cause him too much distress. If you can show respect for his items, rubbish though you believe them to be, and try and store them in a more user-friendly way, it might cheer him up. Then his wardrobe might house his clothes more easily.
I have known several older men who started collecting things after retirement. When they died their then old and frail widows had a lot of trouble getting rid of all their "stuff". If you can start collating it into a shed on shelves now, so he can go and look at it and think about what he wants to mend or whatever he thinks of doing, it may help for later on when you are both much older.
But from what I have learned about hoarding, rule no 1 is -never to interfere with another person's things or tell them what to throw away! They must decide it themselves. Never start by deciding they are a hoarder. They must decide it themselves. Only when there is a danger to health or safety can you try to intervene and then remember to be respectful. These are not your things. These are not your rooms.
Please start trying to see this situation another way. You are calling him a teenager. Don't you love him? Are you dismissing all those years when he worked and you watched those video tapes and when the things now not working were in use? Are you ignoring his life that he shared with you, - that he no doubt was so happy to give to you and be useful doing little jobs like printing out things and sorting out the TV or whatever item went wrong? How can you suddenly rubbish all those 50 years of his adult life, the he worked and was so productive, by saying he's like a difficult teenager? He is getting old and he wants to be the capable man he always was , but the jobs are piling up on him. He can't cope with the money that's being wasted because so much has gone wrong - the printer, TV lamps... He does not like all those videos that were so much pleasure going to waste just because CDs and Blue tooth have taken over and there's more money to pay for all that on a pension that he can't do over-time to boost.
See things from his perspective. If you love him, treat him with respect.