You have two choices here. Either you will need to get very good at figuring out when you will not be able to complete your next rep, or you will need to get some kind of safeties, such as saw horses. The other option when it gets heavy enough is just go to a gym that has a power rack, if one is available to you.
Your squats look okay. You tend to go a little too deep and you need to let your knees go a little further forward. Other than that, things look okay. Shoes will help with your knee position a little.