Foscam IP cameras use NPAPI Chrome plugin that by default is disabled in Google Chrome starting version 42. Even if Foscam plugin is installed, you will get following messages:

This site uses a plugin (application/ipcam-regplugin) that is unsupported.
Plugins are not found, Click me to download

Obviously, downloading and installing the plugin again does not make any difference. There is a temporary workaround that enables NPAPI plugins in Google Chrome and allows to use Foscam cameras with Google Chrome. I say “temporary”, because Google will remove NPAPI support completely starting Chrome version 45. Hopefully by then Foscam will provide a solution.

• In Google Chrome address bar type: chrome://flags and press Enter
• Find item Enable NPAPI Mac, Windows and enable it
  
• Restart Google Chrome

This works for both, Windows and Mac versions of Google Chrome.