stop seeding on opera

That is against the spirit of P2P.
You get to download because someone is uploading. The least you can do is to upload too while downloading.
That way files stay seeded, and others can download them too.

For example, if you download one video file, only that one file is downloaded/shared, nothing else.

When the download is completed you can do right cklick and delete file, it will stop it from seeding. Answered Jan, 20 2011

That is against the spirit of P2P. You get to download because someone is uploading. The least you can do is to upload too while downloading. That way files stay seeded, and others can download them too.
For example, if you download one video file, only that one file is downloaded/shared, nothing else.
If you use BitTorrent, any files within the .torrent file you are downloading will be shared.
Once the download is completed you can rightcklick on it and delete it, it will stop it seeding but the file will stay in your download folder. Answered Jan, 20 2011

There is a setting in the software that you can set the upload speed when nothing is downloading, set it to 1kb to stop uploading. Answered Jan, 24 2011