Hi guys; I have 3k dsl and mostley watch live sports streamings,
i'd like to know in what situations when another pc shares the same internet ip will affect my video streaming? thanks.

Since sharing the same public IP address means you're sharing the same line, you'll be competing for the same last-mile bandwidth.

If the other user(s) start a download or open a large e-mail attachment, you may experience glitches or artifacts or even interruption. Video streaming can be quite the bandwidth hog, so unless you have a fast DSL connection, there could be problems.

Edit: If your DSL provider is using "carrier-grade NAT" you may end up sharing a public IP address with a number of other DSL customers. This will not affect your video streaming or available bandwidth at all (but could cause a number of other services to stop working).

Thanks Ser Olmy:that's what i suspected, (My DSL is 3K) a member of family lives downstair bought a laptop and wanted me to give him my password,but i told him that my bandwidth would suffer if i did and toll him that he should acquire internet for himself,besides they have grand kids coming to his house that i don't trust on what they surf in the internet, and the other day i was just updating my other pc while i was watching a live game and it did start to buffer.

Wise choice. Neighbours asking your password so they can have free internet. Giving them access is a big no no