Similar to the feature for Android users that let images and videos to be backed up to their Google account, Microsoft offers full-resolution image and video backup to SkyDrive for Windows Phone 8 users. The variation is that till now this was not available in all Windows Phone 8 users. Initially, Microsoft has declared that for all Windows Phone 8 users it will make the full resolution backup of photos and videos through SkyDrive. Users who hadn't had access to the backup earlier have already started noticing it on their phone.
Microsoft is telling Windows Phone 8 users to be patient with the company and stated, “This will be a universal feature. The backup capability should be available to all users by this weekend. And while it might already be working for your phone, you will have to enable it by going into the menu of your device. Go to Photos>More> Settings>SkyDrive. “
Those who are having the backup capacity will observe a new look for SkyDrive with a "Best Quality" option for both photos and videos. If user wants to have a full resolution backup of both pictures and video they have to click on the box for "Best Quality" for both image and video. To keep the phone bill down, user needs Wi-Fi for full-resolution backup.
Source : phonearena