Beehive Conferencing works OK with 7u51 but if either 32 or 64 bit 8 GA is installed it won't work.

Try the following. I took these notes with IE but saw the same with Firefox. After each reconfiguration I tried to Join a Beehive Conference using the Quick Start means.

JCP Security slider at bottom (medium), no Exception Site List
32 bit 7u51 + 64 bit 7u51 : OK
add 32 bit 8 GA // slider is reset to middle (high), move it back down
32 bit 8 GA + 64 bit 7u51 : won't work, JAR manifest failure (see Note 1)
add 64 bit 8 GA
32 bit 8 GA + 64 bit 8 GA : won't work, JAR manifest failure (see Note 2)
remove 32 bit 8 GA
32 bit 7u51 + 64 bit 8 GA : won't work, JAR manifest failure
remove 64 bit 8 GA
32 bit 7u51 + 64 bit 7u51 : OK

Slider at middle (high), Exception Site List has https://stbeehive.oracle.com:443
32 bit 7u51 + 64 bit 7u51 : OK
add 32 bit 8 GA
32 bit 8 GA + 64 bit 7u51 : won't work, JavaFX Button failure (see Note 3)
add 64 bit 8 GA
32 bit 8 GA + 64 bit 8 GA : won't work, JavaFX Button failure
remove 32 bit 8 GA // installer prompted to close javaw.exe, then the same as Note 2 but this time from jre8\bin, then installer prompts to close ssvagent
32 bit 7u51 + 64 bit 8 GA : won't work, JavaFX Button failure
remove 64 bit 8 GA // installer prompted to close 2 copies of javaw.exe
32 bit 7u51 + 64 bit 7u51 : OK

Notes:
1) Why is the 64 bit install having an impact when the 32 bit plugin is what's being used? This is the failure:

java.lang.SecurityException: Missing required Permissions manifest attribute in main jar: https://stbeehive.oracle.com:443/bcentral/appdownload/334B:3BF0:capm:38893C00F42F38A1E0404498C8A6612B000693465732
 at com.sun.deploy.security.DeployManifestChecker.verifyMainJar(Unknown Source)
 at com.sun.deploy.security.DeployManifestChecker.verifyMainJar(Unknown Source)
 at com.sun.javaws.Launcher.doLaunchApp(Unknown Source)
 at com.sun.javaws.Launcher.run(Unknown Source)
 at java.lang.Thread.run(Unknown Source)

2) When press Join on conference got IE security popup, "A website wants to load web content using this program on your computer", JRE 7u51, followed by UAC dialog asking if it's OK to run jre7\bin\ssvagent.exe -new -high so I let it run. Then I had to reactivate Join.

3) Console shows

Delegating to Main-class = com.sun.javafx.runtime.main.Main
java.lang.NoSuchMethodError: javafx.scene.control.Button.<init>(Z)V
 at oracle.beehive.rtc.Main$Main$Script.applyDefaults$(Main.fx:93)
 at com.sun.javafx.runtime.FXBase.applyDefaults$(Unknown Source)
 at oracle.beehive.rtc.Main.<clinit>(Main.fx)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at com.sun.javafx.runtime.provider.GUIRuntimeProvider$1.run(Unknown Source)
 at com.sun.glass.ui.Application.invokeAndWait(Unknown Source)
 at com.sun.javafx.tk.quantum.QuantumToolkit.runToolkit(Unknown Source)
 at com.sun.javafx.tk.quantum.QuantumToolkit$12.run(Unknown Source)
 at com.sun.glass.ui.Application$2.run(Unknown Source)
 at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
 at com.sun.glass.ui.win.WinApplication.access$300(Unknown Source)
 at com.sun.glass.ui.win.WinApplication$4$1.run(Unknown Source)
 at java.lang.Thread.run(Unknown Source)