100% doable and easy. In clients like qBittorrent you can right click on a torrent and select both "Download Sequentially" and "Download first and last pieces". Once it downloads the first and last pieces, you can wait for a bit until maybe the first 5% has downloaded, and you can open the file with a decent video player like VLC, and as long as the download is faster than the play speed, it'll play just fine.