You can either tear out your hair when a disaster strikes your hard drive or you can prepare for it ahead of time, but data loss is as inevitable as death and taxes. An online backup service is one of the best ways to protect yourself against such threats as a crashed hard drive or accidental deletion. Natural disasters such as fires, floods, and earthquakes can also spell the end of your digital media and documents. Even if you're among the very few who diligently perform local backups at regular intervals, you could still lose data if you don't store backups offsite.
If you want to download as videos itself, you can use other free tools like Free Youtube Download to download all videos with a single click. Please be careful while installing this tool as it optionally installs a browser toolbar and modifies search preferences. So please make sure you read and uncheck the optional checkboxes while installing to avoid surprises in your browser.