Can you please elaborate more on your question? Or you can copy paste what you have coded and give more collaborative description on what you are expecting.

*collaborative = elaborative

to access the properties of a component in another you should have its reference. Say you have a textBox with id myText in your main mxml file . And you want to access it from some other component you can access access its text property :

//code inside any other component
trace(Application.application.myText)
here Application.application refers to your application root and whatever is there public will be accessible and its properties also.

2)To access a public method
Say a public method (getmyValue) of component i.e myComponent can be accessed using
click"myComponent.getmyValue();"

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"
	xmlns:v="components.*" creationComplete="pecdata.send()">
	<mx:Script>
		<![CDATA[
			import components.ContactusForm;
			import mx.rpc.events.FaultEvent;
			import mx.rpc.events.ResultEvent;
			public var mycoll: XMLListCollection;
			private function resultHandler(event:ResultEvent):void{
				var dp:Object=event.result as XML;
			}
	        private function handleFault(event:FaultEvent):void{
	        	trace(event.fault.faultCode+":"+event.fault.faultString);
			}    
		]]>
	</mx:Script>
		<mx:HTTPService id="pecdata" url="peccontentdata.xml" result="resultHandler(event)" 
						fault="handleFault(event)"  resultFormat="e4x"/>
		<mx:XMLListCollection id="peccoll" source="{pecdata.lastResult.pectab}"/>
		
	
		<v:MyComp id="tabandvideo" width="957" height="100%" x="56" y="107" verticalAlign="middle"/>
		<v:ContactusForm x="57" y="109" height="491"/>
		<v:AskaquestionForm x="57" y="118" width="957" height="100%"/>
		<v:ImageScroll x="57" y="415" width="475" height="86"/>
		
		<mx:ControlBar cornerRadius="10" fontSize="12" color="#344C51" fontWeight="bold" y="726" x="56" width="957">
			<mx:Label text="Ask A Question" click=""/>
			<mx:Label text="|" width="13"/>
			<mx:LinkButton label="Contact Us" click=""/>
			<mx:Label text="|" width="13"/>
			<mx:Label text="Education Center Home" click=""/>
			<mx:Label text="|" width="13" height="20"/>
			<mx:Label text="Schedule Appointment" click=""/>
		</mx:ControlBar>
</mx:Application>
-----------------------------cust component
<?xml version="1.0" encoding="utf-8"?>
<mx:HBox xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:v="components.*" height="300"
	horizontalScrollPolicy="off">
	<mx:Script>
		<![CDATA[
			import mx.collections.ArrayCollection;
			import mx.collections.XMLListCollection;
			import mx.controls.Alert;
			import mx.core.Application;
			
			[Bindable]
			private var dp:Object = Application.application.peccoll; 
			[Bindable]
			private var obj:String;
			private function myEventHandler(event:MouseEvent):void {
		    obj = ((event.currentTarget).getRepeaterItem().@mediahubfile);
		    }  
		]]> 
	 </mx:Script>

	<mx:VideoDisplay id="vid" source="{obj}"  autoPlay="true" width="50%" height="320" bufferTime="0.1"/>
	
	<mx:Panel paddingTop="1" width="50%" height="320" cornerRadius="10" paddingRight="1" borderColor="#CBDDF8" backgroundAlpha="0.3"
		verticalScrollPolicy="off">
		<mx:TabNavigator id="pectabn" width="100%" height="100%" tabHeight="40" horizontalGap="5">
		    <mx:Repeater id="rp" dataProvider="{dp}">
			    <mx:VBox id="rpbox" label="{rp.currentItem.@pectabname}" >
					<mx:Repeater id="rp2" dataProvider="{rp.currentItem.spotdetails}">
						<mx:HBox horizontalGap="8">
							<mx:Image id="img" source="{rp2.currentItem.@mediahubthumbnail}" click="myEventHandler(event)"/>
							<mx:TextArea id="desc" text="{rp2.currentItem.@description}" click="myEventHandler(event)" 
								editable="false" cornerRadius="10" selectable="false" wordWrap="true" width="100%"/>
						</mx:HBox>
			        </mx:Repeater>
			     </mx:VBox> 
			</mx:Repeater>
		</mx:TabNavigator>
		<mx:ControlBar>
		<mx:Text text="PLAY:Select thumbnail above to preview spot."/>
		</mx:ControlBar>
	</mx:Panel>
</mx:HBox> 

i am building the site with flex and my own images more details : http://www.ylysnetworks.com/testpec/

your functions should be public if you want to access them from other parts of application.

if MyComp is your custom component then you can access the components inside your MyComp using MyComp.vid which are public , but if you want to access dataProvider like dp then you should make it public first
public var dp:Object = Application.application.peccoll;

if you want to access Mycomp from ContactusForm you can use script like
parent.document.Mycomp or Application.application.Mycomp or parent.Application.Mycomp