Can't speak for video because I don't really share video on my Pogoplug. However, I can say that I noticed a lag in my internet connection while a friend of mine was trying to download a folder that was about 600 Mb. Maybe the two are related?

This comment is purely based on experience with Pogoplug Pro. Pogoplug does generate thumbnail files (small aize files) for some file types such as jpeg. The thumbnail appears to be used within file hierarchy and pre-view user interfaces. Thumbnails are also used in the iPhone ap file preview. As long as you only view the file or the preview, it would appear Pogoplug only transfers the thumbnail file, which is relatively small size. If you upload or download the file, you will transfer the entire file contents. If the upload or download occurs within the Local Area Network (LAN), Pogoplug doesn't need the Wide Area Network (WAN or internet) to transfer the file. LAN speed can be as much as 10x to 100x quicker than WAN speed -- potentially even quicker.

To make this long story short, when uploading or downloading a file that goes outside of the LAN, Pogoplug will use your internet connection to transfer the file. Depending on your internet service bandwidth, users within the network could experience a temporary reduction in throughput speeds on WAN transfers during the upload/download.

The time it takes to upload/download a file using the internet is dependent on the size of the file, your internet service speed, and over-all internet traffic at a given time of day (among some other factors such as latency). As an example, with a 1 Mbps internet service, in the evening when internet traffic is less, a 2 Meg photo might take about 20-30 seconds to upload/download. Typically a transfer will flow thru 2 different internet provider services (the sender's and the receiver's), therefore the slower of the 2 services will more strongly influence the speed of the transfer. During that 20-30 seconds, other clients using a 1Mbps internet connection might experience significant reduction in response. If instead the service were 10Mbps rather than 1Mbps, clients might not notice much.

Is there a way to 'limit' the upload speed so that the PP does not suck up all the Internet bandwidth? Most FTP or upload/download tools have settable limited to keep the device from being a hog.