You can, if you are not limited by the server side as there are some types of accounts that prevent it. For example, Flickr limits videos to 90 seconds regardless of account type but gives you 500MB per video for Pro account instead of 150MB per video for a free account. BTW, unless you have Pro account on Flickr, your N9/N950 videos could not be viewed in their glory when uploaded to Flickr because HD video playback is only available for Pro accounts.