input-selector: API looks good to me except for the select-all property. IMHO it should go away, it's only for a very specific use case and the farsight funnel element does exactly this.
We should add the GstSelectorPad to the docs somehow, the pad subclass has some useful properties.

output-selector: Looks good too but it might be a good idea to add correct setcaps/getcaps functions to the pads

Created attachment 177523 [details] [review]
output-selector: Add pad-negotiation-mode property

Adds getcaps/setcaps to output-selector and adds a property
to select which type of negotiation should be done.

The available modes are:
 * none:   no negotiation (current behavior), getcaps return ANY and
           setcaps aren't set on any of the peers
 * all:    use all pads (default), getcaps returns the intersection of
           peer pads and setcaps is set on all peers
 * active: getcaps and setcaps are proxied to the active pad

Renamed the actual enums in the code a bit (not sure it matters here though):

commit 757dc90faa163a235e1d16791a0a0f8c74715768
Author: Thiago Santos <thiago.sousa.santos@collabora.co.uk>
Date:   Tue Jan 4 12:42:50 2011 -0300

    output-selector: Add pad-negotiation-mode property
    
    Adds getcaps/setcaps to output-selector and adds a property
    to select which type of negotiation should be done.
    
    The available modes are:
     * none:   no negotiation (current behavior), getcaps return ANY and
               setcaps aren't set on any of the peers
     * all:    use all pads (default), getcaps returns the intersection of
               peer pads and setcaps is set on all peers
     * active: getcaps and setcaps are proxied to the active pad
    
    https://bugzilla.gnome.org/show_bug.cgi?id=638381

commit c8ffd4e395261cdf6a88ac3ff13539fcc3add5cc
Author: Tim-Philipp Müller <tim.muller@collabora.co.uk>
Date:   Thu Jan 6 18:18:29 2011 +0000

    docs: mention extra input-selector pad properties
    
    https://bugzilla.gnome.org/show_bug.cgi?id=638381