I've been looking for some time for this,
Today i've found a working solution.
To enable 1080p on youtube app change this on your build.prop:
ro.product.model=Nexus 10
ro.product.brand=google
ro.product.name=mantaray
ro.product.device=manta
ro.product.board=manta
ro.product.manufacturer=samsung
Reboot, try changing quality on youtube by click the three dots on the top right corner.
side effects:
Kodi isnt
running installing, to solve this you can install kodi with the stock build.prop and only then edit it
Here is a build.prop backup from CM11:
# begin build properties
# autogenerated by buildinfo.sh
ro.build.id=KTU84Q
ro.build.display.id=cm_ouya-userdebug 4.4.4 KTU84Q 2d6bbf118a test-keys
ro.build.version.incremental=2d6bbf118a
ro.build.version.sdk=19
ro.build.version.codename=REL
ro.build.version.release=4.4.4
ro.build.date=Mon Nov 2 04:55:40 CET 2015
ro.build.date.utc=1446436540
ro.build.type=userdebug
ro.build.user=jenkins
ro.build.host=milaq
ro.build.tags=test-keys
ro.product.brand=Boxer8
ro.product.name=ouya
ro.product.board=cardhu
ro.product.cpu.abi=armeabi-v7a
ro.product.cpu.abi2=armeabi
ro.product.manufacturer=Boxer8
ro.product.locale.language=en
ro.product.locale.region=US
ro.wifi.channels=
ro.board.platform=tegra
# ro.build.product is obsolete; use ro.product.device
ro.build.product=ouya
ro.product.model=Ouya
ro.product.device=ouya
# Do not try to parse ro.build.description or .fingerprint
ro.build.description=ouya-user 4.4.2 KOT49H 937116 release-keys
ro.build.fingerprint=boxer8/ouya/ouya:4.4.2/KOT49H/937116:user/release-keys
ro.build.characteristics=tablet
ro.cm.device=ouya
# end build properties
#
# from device/boxer8/ouya/system.prop
#
#
# system.prop for ouya
#
ro.carrier=wifi-only
ro.sf.lcd_density=213
ro.cwm.forbid_format=/boot
tf.enable=y
ro.bq.gpu_to_cpu_unsupported=1
ro.zygote.disable_gl_preload=true
### > resolution and overscan settings
### uncomment line below to boot with 1280x720
#persist.tegra.hdmi.resolution 720p
### uncomment both lines below and tune overscan.val [0.00 - 0.20] for overscan correction
#persist.sys.hdmi.overscan 1
#persist.sys.hdmi.overscan.val 0.1
### < resolution and overscan settings
#
# ADDITIONAL_BUILD_PROPERTIES
#
ro.rommanager.developerid=cyanogenmod
ro.com.google.clientidbase=android-google
keyguard.no_require_sim=true
ro.url.legal=http://www.google.com/intl/%s/mobile/android/basic/phone-legal.html
ro.url.legal.android_privacy=http://www.google.com/intl/%s/mobile/android/basic/privacy.html
ro.com.android.wifi-watchlist=GoogleGuest
ro.setupwizard.enterprise_mode=1
ro.com.android.dateformat=MM-dd-yyyy
ro.com.android.dataroaming=false
ro.build.selinux=1
persist.sys.dalvik.multithread=false
persist.sys.dun.override=0
persist.sys.root_access=1
ro.cm.version=11-20151102-UNOFFICIAL-ouya
ro.cm.releasetype=UNOFFICIAL
ro.modversion=11-20151102-UNOFFICIAL-ouya
ro.cmlegal.url=https://cyngn.com/legal/privacy-policy
persist.sys.recovery_update=false
ro.cm.display.version=11-20151102-UNOFFICIAL-ouya
ro.config.notification_sound=Argon.ogg
ro.config.alarm_alert=Hassium.ogg
ro.carrier=unknown
wifi.interface=wlan0
wifi.supplicant_scan_interval=15
ro.opengles.version=131072
persist.sys.usb.config=mtp,adb
dalvik.vm.heapstartsize=8m
dalvik.vm.heapgrowthlimit=64m
dalvik.vm.heapsize=384m
dalvik.vm.heaptargetutilization=0.75
dalvik.vm.heapminfree=512k
dalvik.vm.heapmaxfree=8m
persist.sys.dalvik.vm.lib=libdvm.so
dalvik.vm.lockprof.threshold=500
dalvik.vm.dexopt-flags=m=y
net.bt.name=Android
dalvik.vm.stack-trace-file=/data/anr/traces.txt
