By adding IPFS to your computers and pinning files, you're actively making DTube decentralised. As you guys should know, every video is hosted on a main server and the gateways grab those video files from it. If you pin a file by upvoting, this will allow DTube to download from you and others who have pinned the same video file and reduce the centralization of that server. If enough people pin and support the network, the main server would essentially operate as a very reliable backup to be leveraged on, if the network needs it.
It's up to you guys now. The gateways need to have the files before you can watch the content. If it doesn't have it, it needs to download it from somewhere. The more sources the gateways can download from, the faster the gateways can give you the content. Help the network and we might see miracles performed.