A torrent works by breaking a file into small chunks, each of which can be shared between peers. This speeds up downloads because peer A could be sharing chunk 1 with you while peer B could be sharing chunk 8 with you etc. (See BitTorrent and Torrent file.)

The torrent client would need to reconstruct the file in order for you to use it.

None of the chunks is useful on its own. Each is typically 1/1000th - 1/2000th of the entire video file. None is generally even viewable as video without adjacent chunks due to the type of video codecs in common use.

In Canada, is it copyright infringement to use a modified (say, self-written) torrent client that simply downloads the chunks and immediately discards them from memory upon receipt, never storing any chunk on disk, and never reproducing any portion of the original file larger than an individual torrent chunk, and doesn't host or otherwise make the chunk available to other users.

Does the analysis change if you only download and immediately discard one of the chunks?

To simplify answers, let's assume that the fair dealing user right is not implicated.