You can easily upload photos and videos to Flickr by using Web Uploadr. Flick allows you to access your photos in different sizes. It re-size your photos to more web-friendly dimensions. Each photo has a 75x75 and 150x150 square thumbnails and 100-, 240-, 320-, 500-, 640- 800*-, 1024-, 1600*- and 2048*-pixel versions, and your original photo file. To access your original Flickr photos, go to your profile and view an individual photo page. Click 'More' menu and then click 'View all sizes' option. You can download your original photos at any time. Flickr allows you to use the 'Global Setting' in your accounts to specify 'who can download original photos'. It provides you several options such as 'Only you', 'Your Friends ad Family', 'Your Contacts', 'Any Flickr User' or 'Anyone'. Flickr offers 'Creative Commons' license to your photo. If you attached this license to your photo indicating that you are OK with sharing it, then anyone will be able access, share and download your photo. Flickr has 'Image size settings' which allows you to set the maximum size limit displayed to viewers of your photo.
You can install PicBackMan's Flickr uploader for Mac from the website and start backing up photos and videos.